Jason Reed / Reuters

Tammy Duckworth, D-Ill., U.S. representative-elect for Illinois' 8th Congressional District, is pictured with other female members of Congress on Capitol Hill in Washington on Nov. 14. Duckworth, a helicopter pilot in the Iraq war who was shot down and lost both her legs in the attack, is the first disabled woman to be elected to the House of Representatives.

When Tammy Duckworth steps into Congress this January for her first term, she’ll be carried by two prosthetic legs – and the potent notion that if she can survive a grenade blast while piloting a chopper, she surely can endure any political flak on Capitol Hill.

“The worst day for me in Washington on the floor of the House is never going to be as bad as me getting blown up. So bring it,” said Duckworth, a Democrat who represents Illinois’ 8th Congressional District, the suburbs north of Chicago.

One of the first women to fly combat missions in Iraq, Duckworth’s Black Hawk was hit by enemy fire in November 2004 as the aircraft skimmed tree tops at about 135 miles per hour. The explosion vaporized her right leg, smashed her left leg into the instrument panel, sheering it off, and tore away most of her right arm. Before losing consciousness, she used her remaining arm to try to land the sputtering chopper. On Nov. 6, she won election to the U.S. House.

“There’s nothing anyone can say to me or do to me — short of actually pointing a gun and shooting at me — that’s going to be as bad as it was in Iraq and that year I spent recovering. So it’s really freeing,” Duckworth told NBC News. “Had you talked to me 10 years ago, before I served and got hurt in combat, I would not have the courage to do what I’m doing now.”

The sudden violence of her final mission — followed by months of surgeries, (doctors reattached her arm), and rehab at Walter Reed Army Medical Center — imbued Duckworth, 44, with an intimate understanding of warfare’s true cost, a sensibility that’s fast vanishing from both chambers of Congress.

**

In 1977, the 435-seat U.S. House of Representatives contained 347 veterans (almost 80 percent of that body) while 65 former service members filled the 100-seat U.S. Senate.

In 2013, 84 fellow veterans will join Duckworth in the House (19 percent) while the Senate’s cadre of ex-military personnel has dwindled to 18, according the American Legion.

“That’s incredible,” said Paul Rieckhoff, founder and executive director of Iraq and Afghanistan Veterans of America, a nonpartisan and nonprofit group with more than 200,000 members. “The volunteer military has been great for our military, but maybe it’s not great for our democracy.”

The rapidly shrinking corps of congressional veterans threatens to dampen the attention Washington pays to tens of thousands of men and women yet to return from Afghanistan and, Rieckhoff added, to more than 2 million post-9/11 veterans — many of them tormented by combat-related stress and troubled by sluggish hiring rates, Rieckhoff said.

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“A low number of veterans in Congress is bad for everybody. It’s bad for the veteran community. It’s bad for the active-duty military. It’s bad for America,” Rieckhoff said. “I am concerned that as the number continues to decline, we will have fewer advocates.”

At the same time, however, Duckworth’s election gives what Rieckoff calls the “new veterans movement” a truly historic moment and some vital momentum.

“That’s not just because she is a woman and it’s not just because she is a disabled vet,” he said. “It’s because she’s become such an important spokesperson for our entire community — beyond politics.”

**

Inside the cockpit of the crippled Black Hawk, all internal communications were dead.

Duckworth wasn’t sure if she was the lone survivor. Smoke swirled. The floor of the helicopter had been ripped open by a rocket-propelled grenade. She spotted a field where she thought she could ease the aircraft down. She tried to work the controls. She didn’t know that Chief Warrant Officer Dan Milberg was alive as well, had glimpsed the same clearing and was steering the Black Hawk toward safe ground.

Duckworth also believed she was uninjured. She could still feel her legs. 

Before losing consciousness, Duckworth remembers completing a final task after the chopper had come to rest. She raised her left arm to perform an emergency shutdown of the electronics. She worried about a fire consuming the other five soldiers still strapped into their seats.

She has no recollection of arriving at the emergency room in Baghdad where — Duckworth later was told — she demanded that medics give her a full update on her crew. Her remaining memories are some of her worst, coming at Walter Reed, during a slow surfacing from her induced coma.

Before anybody near her bed realized Duckworth could again see and hear, she watched and listened for two days as doctors and nurses mentioned “a helicopter crash.”

"To a pilot, a crash is very different from a forced landing. At the time, I didn’t know Dan was OK. But I did know my crew chief was badly hurt and had almost lost his leg. I had been told I’d lost my legs,” Duckworth said. “But I kept hearing talk about a helicopter crash. I thought: ‘Oh my God, I crashed the helicopter. I didn’t do my job.’ I spiraled into a depression, laying there in that intensive care unit where I just thought: ‘I deserve to lose my legs. I must have crashed the aircraft. I am a complete and utter failure and I hurt my men.’ ”

Her husband, Maj. Bryan Bowlsbey, a fellow Army National Guardsman, was by then at her side. He noticed she was crying. He tried to cheer her with descriptions of amputees running atop artificial legs. She told him her misery was rooted in the crash, not her devastating injuries. Bowlsbey gently corrected her: She had been on the controls as Milberg had managed to settle the aircraft onto the Iraqi field. She had done her duty.

“I’ve been fine ever since,” Duckworth said. “Nothing you can do to me now can ever negate that. I just have this freedom in my life because of that day and what I’ve been through. In a very weird way, it’s a gift.”

**

The 2012 presidential election marked the first since 1932 in which no veterans held spots on the Democratic or the Republican tickets. The last time: When Herbert Hoover lost to Franklin D. Roosevelt.

But that trend has been speading inside the legislative branch for 40 years. 

“The declining population of veterans in Congress creates an even wider divide between our veteran community and the majority of the American public,” said Louis J. Celli, Jr., national legislative director for the American Legion.

“Congressional members who have worn the uniform of our nation tend to have a better understanding of the unique challenges and needs faced by the veteran community, especially those veterans who return with medical needs that extend beyond their active service period,” Celli added.

While veterans groups like IAVA acknowledge that civilian politicians can become champions of military and homefront causes, Celli said, however, “it is usually a long process educating them regarding the difference between earned benefits and sympathy legislation.”

**

As the highest-ranked amputee at Walter Reed, then Maj. Duckworth began handling personal issues for other wounded soldiers in 2005, including salary snags and the potential losses of their homes. 

She called Illinois Sen. Dick Durbin so often to ask for his help, he eventually gave her his business card scrawled with his cell phone number. Through her advocacy for other veterans, she also met then-Illinois Sen. Barack Obama.

Paul Beaty / AP

Congresswoman Tammy Duckworth, representative for Illinois 8th District seat, talks to the media in Elk Grove Village, Ill., Tuesday, Nov. 6, 2012.

“I was just doing it because it was my job,” Duckworth said. “In August of ‘05, I get a call from Senator Durbin who said: ‘You know, if things are as bad as you say they are for veterans, then you need to do something about it.’ I said, ‘Well, yes sir, I’m calling you.’ He said, ‘No, you need to run for office.’ Barack and I think you should run.’ ”

She narrowly lost her first bid for Congress in 2006.

Days ago, as she and other freshman congressional members gathered for a group photo on Capitol Hill, Duckworth met former Marine Col. Paul Cook — the new Republican representative whose district covers Highland, Yucaipa, the San Bernardino Mountains, the entire High Desert.

“He’s a Vietnam vet. We just hit it off,” Duckworth said. “There’s a subset of us who have seen direct combat action. He started talking about walking into a trip wire in Vietnam and wanted to know what hit me. He asked: ‘What that was like?’ When you’ve both seen combat action, you have this common place.”

Simply put: War stories can trump political parties.

Duckworth lists two primary heroes: retired Republican Sen. Bob Dole and Democratic Sen. Daniel Inouye from Hawaii, both disabled veterans.

“They are two men who recovered in the same hospital after World War II and who went on to pass legislation nationally,” she said. “They found a way to come to middle ground because of their shared experience. So I hope that with the Iraq and Afghanistan veterans coming into Congress, we also will be able to work together.” 

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An investigation is underway after someone called in a bomb threat to the Walter Reed National Military Medical Center in Bethesda, Md., on Wednesday morning.

A Walter Reed spokesperson said someone called the center at 8:50 a.m. ET and said something was going to explode at 10 a.m. The center's Building 19, known as the America building, was evacuated and explosive detection dogs were brought in.

Authorities did not find a bomb in the first search of the building, which is for outpatient services. A Navy official said a second search was conducted as an extra precaution.

The center was given the "all clear" at 12:50 p.m. Medical appointments resumed at 1:00 p.m.

No information is available about the person who called in the threat, Reuters reported.

Walter Reed is among the nation's largest military medical centers, and last year the facility made the move from Washington, D.C. to nearby Bethesda, Md. After operating for more than a century, the center is expected to close for good.

NBC News' Courtney Kube and Reuters contributed to this report.

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By Jim Miklaszewski, NBC News chief Pentagon correspondent

Walter Reed Army Medical Center, a name synonymous with military medicine, took one step closer Wednesday to shutting its doors for good.  In a bittersweet "casing of the colors" ceremony, Army officers packed up their unit flags, never to be flown again over Walter Reed.

For more than 100 years, from World War I to Iraq and Afghanistan, Walter Reed provided medical care for hundreds of thousands of US military wounded.

"All the warriors have passed through here," Walter Reed's commander, Col. Norvell Coots, told NBC News.  "This has been a healing place for all of them."

AP

Maj. Walter Reed, circa 1875. for whom the medical center was named.

Dedicated in 1909, the Army hospital was named for Maj. Walter Reed, who discovered that mosquitoes were the source of yellow fever, which plagued American military forces in Cuba following the Spanish-American war.  Reed himself died of an infection from appendicitis seven years before the hospital was built.

With an original capacity of only 80 beds, Walter Reed was expanded to a sprawling 113 acres, now providing care for 700,000 patients per year.

Walter Reed is also an invaluable piece of American history. World War I Gen. John "Blackjack" Pershing lived in a three-room suite in the main hospital building for seven years before he died in 1948. Historian Dr. John Pierce said that although Pershing retired, he was often sought out for military advice. "Two-star Gen. George S. Patton came here to this room, got down on his knees, and General Pershing blessed him before he went off to World War II," according to Pierce.

President Dwight Eisenhower had his own suite in Ward 8, a high-security section of the main hospital.  Eisenhower was confined to the hospital for 11 months before he died in 1969.

See a slideshow of images from Walter Reed's long history

During the Civil War, the ground on which the hospital was later built was actually an encampment for the Confederate Army on the outskirts of Washington, D.C. Col. Coots recounts that in 1864, a rebel sharpshooter climbed to the top of a tulip tree and fired off a round at President Lincoln standing in a parapet at a Union Army base nearby. The shot missed, but a young lieutenant pulled Lincoln down and, as history tells it, shouted, "Get down, you damned fool. The country can't afford to lose a president."

In the past 10 years, 18,000 service members wounded in the wars in Iraq and Afghanistan flooded Walter Reed. Advances in battlefield medicine had dramatically improved survivability rates. The former chief of Walter Reed's critical care nursing, Col. Rosemary Edinger, told NBC News, "During Vietnam, the soldiers we get back today would not have survived the battlefield."  But she also acknowledged, "The nature of the wounds, the amputees, is truly staggering at times."

The stress on Walter Reed's medical services also was staggering.  In 2007 a scandal broke over substandard housing conditions for Walter Reed outpatients.

Defense Secretary Robert Gates fired Army Secretary Francis Harvey over the scandal. Outpatient care was ultimately improved Army-wide.

Jim Watson / AFP/Getty Images

Marine Cpl. Chris Santiago, center, waits in the fitting clinic at Walter Reed. He was injured in Iraq.

Five years ago, a Pentagon commission determined that the aging Walter Reed should be closed to cut costs. The remaining 150 of the most seriously wounded patients will be transferred in August to a new expanded facility at the Bethesda Naval Hospital to be named the Walter Reed National Military Medical Center. 

The 113-acre Walter Reed campus, on the western outskirts of the nation's capital is prime real estate. The city will claim most of it for commercial development and housing. The State Department will take over the rest to provide offices and housing for visiting diplomats.

Pierce fears that in the handover, much of Walter Reed's history will be lost. "It's a big loss, it really is. I guess I just have to accept it – grudgingly."

But Col. Coots is confident of the medical center's legacy.

"Once you've been at Walter Reed, you can't get Walter Reed out of you," he said. "It's a part of your spirit forever."