Tammy Duckworth, a Democratic representative from Illinois who was raised in Hawaii, said Monday she will challenge Republican Senator Mark Kirk in 2016. If she wins, she will become the second female combat veteran ever elected to the Senate.

The first is Republican Joni Ernst, who won an Iowa Senate seat in November. A lieutenant colonel in the Iowa Army National Guard, Ernst, 44, served as company commander of a unit running convoys from Kuwait into southern Iraq in 2003-2004. 

Duckworth, a 47-year-old retired lieutenant colonel in the Illinois Army National Guard, deployed to Iraq and lost both legs when her helicopter was shot down there in 2004.

Ernst and Duckworth’s entrance into the spotlight comes as the overall number of veterans in Congress is on the decline, but as veterans of the post-9/11 wars in Iraq and Afghanistan–women and men–find roles in Washington.

In 2012, Duckworth and Tulsi Gabbard, a Democrat from Hawaii, became the first female combat veterans elected to the House, according to the RutgersCenter for American Women and Politics. (Three past female representatives had served in non- combat roles, according to the center.) In 2014, they were joined by Arizona Republican Martha McSally, who was the first woman to fly in combat for the Air Force.

Duckworth has said her experience in the military prepared her to stick to her guns in politics.

“I think my willingness to take that stand does come out of my military background, that sometimes you’ve got to stand up to the boss and say, ‘Sir, I disagree. That’s the wrong thing to do,'” she told Politico last year. 

McSally has similarly said that Air Force values frame her public service. “Service before self, integrity and excellence in all we do” are “the character traits that are sorely lacking” in Washington, she told the Associated Press in 2013.

Overall, the number of veterans in Congress has declined over the past 25 years, according to PBS and Pew Research Center. After the fall elections, the 114th Congress was on track to have 97 current and former service members, down from 108 veterans in the previous Congress. That was still a higher proportion that that of veterans in America overall–7 percent as of the last Census.

The Cook Political Report, a nonpartisan outlet that analyzes elections, rated the 2016 Illinois Senate race as leaning in favor of Kirk, just slightly less competitive than a toss-up, as of Friday.

Bloomberg Government contributed to this report.