(CNN) When Joe Biden pledged at the final Democratic primary debate to select a woman as his running mate, Illinois Sen. Tammy Duckworth was rarely mentioned as a contender.
But that is changing as Biden and his campaign move closer to a decision that is expected to come early next month.
Duckworth, 52, is among the broad tier of those being vetted by the Biden campaign. She would be the first woman of color nominated for that high office if chosen. She has served as the junior United States senator for Illinois since 2017. An Iraq war veteran, Duckworth was the first Thai-American woman elected to Congress, the first female double-amputee in the US Senate and the first senator to give birth while in office.
Biden's announcement that he would pick a woman in March was largely greeted with cheers, but the terms of an intra-party debate over representation at the top of the ticket have sharpened over the past few months. The question now -- one that has been amplified by more than a month of anti-racist protests around the country -- is whether Biden should narrow his slate to women of color -- and, more specifically, Black women.
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On Sunday, Duckworth, who is Thai-American, passed when asked by CNN's Dana Bash whether Biden should pick a Black woman for the position.
"The Biden campaign have their own process that they're going through. And I'm sure Vice President Biden will pick the right person to be next to him as he digs this country out of the mess that Donald Trump has put us in," Duckworth said.
Pressed for a more direct answer, Duckworth didn't budge, saying that Biden "knows best" what he needs from a running mate that it was not on "any of us to dictate to him."
The Biden campaign declined to comment.
Her potential candidacy comes as a number of prominent Black leaders have publicly suggested that he pick a Black running mate and Sen. Kamala Harris, former Obama White House national security adviser Susan Rice, Atlanta Mayor Keisha Lance Bottoms and 2018 Georgia Democratic gubernatorial nominee Stacey Abrams, have been among those reported to be in the running.
In late April, Harris, widely viewed as the frontrunner at this stage, said in an interview she believed it "is important to have a woman of color, or a woman," on the ticket -- but declined to go any further.
"I'm not gonna tell Joe Biden what to do," Harris said. "I want him to pick the running mate that that is best equipped to help him win because more than anything Joe Biden has got to win, we cannot suffer another four years of Donald Trump in the White House."
Jill Biden has appeared with at least four women currently thought to be in the running to join the former vice president on the Democratic ticket, including Duckworth, in virtual campaign events and fundraisers over the past few months. Last week at a virtual fundraiser, Jill Biden highlighted Duckworth's military service and said the senator inspires people across the nation.
"Tammy, it's been such a pleasure getting to know you over the years, especially in our work on Joining Forces," Jill Biden said.
"And you have served our nation in so many ways, in the Army, at Veterans Affairs and on Capitol Hill. And as a veteran, a disability advocate and a woman of color, and the first woman to have a child while serving in the Senate, you inspire so many people across this country, and we are honored to have your support."
Born in Bangkok, Thailand, to a Thai mother and American father, Duckworth grew up in Southeast Asia. Her father was a US Army veteran who came to the region to fight in Vietnam and then stayed to work assisting refugees. Duckworth's family eventually moved to Hawaii when she was in high school, and Duckworth said her family relied on food stamps growing up.
"Growing up, my family relied on food stamps -- now called SNAP -- to survive. Glad to join my colleagues&call on @USDA to ensure SNAP recipients can receive grocery deliveries&curbside pickup during the #COVID19 crisis. No one should struggle to get food right now b/c they rely on it," Duckworth tweeted in May.
She graduated from the University of Hawaii in 1989 with a Bachelor of Arts in political science and later received a Master of Arts in international affairs from George Washington University's Elliott School of International Affairs. Duckworth completed a PhD in Human Services at Capella University in March 2015.
In 2004, Duckworth was deployed to Iraq as a Blackhawk helicopter pilot for the Illinois Army National Guard. In November of that year, Duckworth's helicopter was hit by a rocket-propelled grenade and she lost both of her legs and partial use of her right arm. Duckworth was awarded the Purple Heart that year, and served in the Reserve Forces for 23 years.
After running for Congress unsuccessfully in 2006, Duckworth was appointed by then-Gov. Rod Blagojevich to head the Illinois Department of Veterans' Affairs. She served in the position for three years, and then in 2009, then-President Barack Obama appointed Duckworth as the assistant secretary of the US Department of Veterans Affairs.
Duckworth was elected to Congress in 2012, defeating then-Rep. Joe Walsh, a Tea Party Republican and conservative talk radio host. She served two terms representing Illinois's 8th Congressional District before being elected in 2016, handily unseating Republican incumbent Mark Kirk.
In April 2018, Duckworth became the first US senator to give birth while in office. Later that month, she also became the first lawmaker to cast a vote on the Senate floor with her baby by her side. Duckworth spearheaded a successful push to change longstanding rules to allow newborns for the first time onto the Senate floor during votes.
She has been a fierce critic of President Donald Trump. On Sunday, Duckworth condemned Trump's divisive message at Mount Rushmore over the weekend, saying his "priorities are all wrong" and adding that he has failed in his response to the coronavirus pandemic.
"What really struck me about the speech that the President gave at Mount Rushmore was that he spent more time worried about honoring dead Confederates than he did talking about the lives of the 130,000 Americans who lost their lives to Covid-19 or by warning Russia off of the bounty they're putting on American's heads," Duckworth told CNN's Dana Bash on "State of the Union." "I mean his priorities are all wrong here. He should be talking about what we're going to do to overcome this pandemic. What are we going to do to push Russia back? And instead he had no time for that."
In November 2018, Duckworth told CNN the President has "failed miserably" in supporting US troops and their families. She called Trump a "coward" and said he "used his privilege" to repeatedly defer military service.
Duckworth has been critical of the war she fought. In a Politico op-ed, she called out federal leaders for glossing over the cost -- in blood and money -- of ongoing conflicts in Iraq and Afghanistan.
"Our efforts in Iraq cost our economy more than a trillion dollars, and we will be caring for our Iraq and Afghanistan veterans for at least the next 50 years. The next time we go to war, we should truly understand the sacrifices that our service members and the American people will have to make," she wrote. "Which is why, when my colleagues start beating the drums of war, I want to be there, standing on my artificial legs under the great Capitol dome, to remind them what the true costs of war are."
Duckworth is a founding co-chair of the Environmental Justice Caucus, and serves on the Senate Democrats' Special Committee on the Climate Crisis, Armed Services Committee, Committee on Environment & Public Works, Committee on Commerce, Science & Transportation, and Committee on Small Business & Entrepreneurship.
In early May, Duckworth called for a fix to be made to the CARES Act, the coronavirus stimulus package that was passed in March, to provide immediate help to families with newborn babies. The senator also recently sponsored a bill to prohibit the Secretary of Veterans Affairs from charging veterans copayments for preventive services relating to Covid-19.
The pressure on Biden to make history with his choice -- there have been two women vice presidential candidates, both White -- has occasionally thrust others in the field, like Sen. Elizabeth Warren, into politically sticky conversations.
In June, Warren was asked by WCVB in Boston if she believed that Biden should select a woman of color. Not wanting to rule herself out, the Massachusetts senator was noncommittal, saying it was Biden's decision to make.
"Every woman being considered is extremely qualified and would be an asset for the vice president both in his campaign for the presidency and in the White House," Warren told WCVB. "Whoever he chooses, I am 100% committed to doing what it takes to electing Joe Biden and helping elect Democrats up and down the ballot. I am all in."
Abrams, who has been uniquely forthright in touting her qualifications for the post, has given the most direct answer to the question over race. During an appearance on "The View" in April, co-host Sunny Hostin, who is Black and Puerto Rican, who asked if Abrams would consider it "a slap in the face to the Black female voters who are credited, really, for reviving his candidacy" if Biden didn't choose a Black woman for the ticket.
"I would share your concern about not picking a woman of color, because women of color -- particularly Black women -- are the strongest part of the Democratic Party, the most loyal, but that loyalty isn't simply how we vote," Abrams said. "It's how we work, and if we want to signal that that work will continue, that we're going to reach not just to certain segments of our community, but to the entire country, then we need a ticket that reflects the diversity of America."
Minnesota Sen. Amy Klobuchar, as she announced her exit from consideration for the slot, was less circumspect. She called on the former vice president to select a woman of color.
"I truly believe, as I actually told the vice president last night when I called him, that I think this is a moment to put a woman of color on that ticket," Klobuchar said in an interview on MSNBC. "And there is so many incredibly qualified women."
Klobuchar's statement was widely read as less prescriptive than further evidence of where the Biden campaign was already headed.