US President Joe Biden’s weekend decision to drop his reelection bid and endorse Vice President Kamala Harris to replace him as the Democratic candidate leaves Harris with a major, immediate decision: whom to pick as her running mate.

Harris has enlisted the law firm of Eric Holder, the former attorney general, to vet possible running mates, sources told Reuters.

These are some of the top people being discussed, according to people familiar with internal policy discussions.

Andy Beshear, governor, Kentucky

Kentucky’s Democratic governor, Andy Beshear, has carved a successful political career in a heavily Republican state that voted for Republican Donald Trump by a margin of more than 25 percentage points in 2020.

Beshear has touted his record of bringing jobs to Kentucky, supporting public education, and expanding healthcare access. As governor, he has vetoed legislation banning abortions and gender-affirming care for transgender youth, although the vetoes were overridden by the Republican-dominated legislature.

Beshear endorsed Harris on Monday, saying she could help the country “move on to something better.” Asked if he would consider the vice presidency, he told MSNBC that he loved serving his state but added: “The only way I would consider something other than this current job is if I believed I could further help my people and to help this country.”

Pete Buttigieg, US Secretary of Transportation

Secretary of Transportation Pete Buttigieg built a strong fan base among Democratic Party voters during his 2020 primary run against both Biden and Harris, winning the first-in-the-nation Iowa caucus.

Seen as a polished defender of Biden policies, Buttigieg later endorsed Biden and was picked to join the incoming administration’s cabinet in 2021. The former mayor of South Bend, Indiana, also has ties in Michigan, a critical state for Democrats in November.

On Sunday, Buttigieg backed Harris’ candidacy, saying, “Harris is now the right person to take up the torch, defeat Donald Trump, and succeed Joe Biden … I will do all that I can to help her win.”

Roy Cooper, governor, North Carolina

North Carolina Governor Roy Cooper has won praise from Democrats for his strong focus on economic development and his ability to win relatively strong approval ratings in a politically competitive state that leans Republican and voted for Trump in both 2016 and 2020.

“If you want a nominee who can put Donald Trump’s destruction of Roe at center stage, if you want a nominee who actually prosecuted criminals like Donald Trump, and if you want a nominee who can put Trump’s age and fitness in the forefront, Kamala Harris is the person,” Cooper told MSNBC on Monday, one day after speaking with Harris and announcing his endorsement. The US Supreme Court overturned Roe v. Wade abortion rights in 2022.

Mark Kelly, US senator, Arizona

Senator Mark Kelly is liked among Democratic Party elites for striking a relatively moderate tone in a hotly contested state that traditionally has favored Republicans, but which Biden won in 2020.

A former US Navy captain and astronaut, Kelly is also the husband of former US Representative Gabrielle Giffords, who was seriously wounded in a 2011 shooting. Gun violence is a major campaign issue for Democrats.

“I couldn’t be more confident that Vice President @KamalaHarris is the right person to defeat Donald Trump and lead our country into the future. She has my support for the nomination, and Gabby and I will do everything we can to elect her President of the United States,” Kelly wrote in a social media post on Sunday, referring to his wife.

William McRaven, US Navy Admiral (Retired)

Best known as the commander of the military raid in Pakistan that killed Osama bin Laden in 2011, Retired US Navy Admiral William McRaven stands out as the major figure from outside of politics believed to be making the shortlist.

His extensive experience on national security issues included directing coordinating special operations with NATO and Washington’s European allies, as well as running strategic planning for counterterrorism efforts at the White House National Security Council. After leaving government, he served as chancellor of the University of Texas System and was critical of the Biden administration’s chaotic withdrawal from Afghanistan.

He has also been critical of Trump. “I have been a vocal critic of the former president, but I took no joy in seeing him found guilty,” McRaven wrote in June after Trump was convicted in New York of falsifying documents to cover up a payment to silence a porn star ahead of the 2016 election.

“If we are going to continue to be viewed as exceptional, then it is time for both sides to lay down their rhetorical arms and find a way to rise above.”

Josh Shapiro, governor, Pennsylvania

Josh Shapiro, Pennsylvania’s governor, took office just last year but is already seen as a rising national star for the party. Trained as a lawyer, Shapiro served as the state’s attorney general, a legal background similar to Harris’ own as a prosecutor. He has a history of winning elections against Republicans in a state that Democrats believe they must win to secure the election in November.

Shapiro and Harris spoke on Sunday, according to a source familiar with the matter.

“I’ve known Kamala Harris for nearly two decades - we’ve both been prosecutors, we’ve both stood up for the rule of law, we’ve both fought for the people and delivered results. Kamala Harris is a patriot worthy of our support,” he said in a statement on Sunday.

JB Pritzker, governor , Illinois

Billionaire Illinois Governor JB Pritzker has proven a major force in the party, tapping his own financial resources linked to Hyatt Hotels to help Biden’s campaign effort and to support the Democratic National Convention in Chicago next month. While Illinois leans heavily Democratic, neighboring Wisconsin is one of the biggest prizes in the 2024 election.

Endorsing Harris on Monday, Pritzker said the two had spoken and that he felt it was important for the US to elect a woman as president.

“Harris has proven, at every point in her career, that she possesses the skills, strength, and character to lead this country and the vision to better the lives of all Americans … she represents our party’s best chance to defeat Donald Trump.”

Tim Walz, governor, Minnesota

Minnesota’s Democratic governor, Tim Walz, also would bring to the presidential ticket a record of defeating Republicans in a Midwestern state. A veteran of the US Army National Guard, Walz previously represented in Congress a vast, rural, and Republican-leaning district.

“Thanks for the call, @KamalaHarris,” he said on social media on Monday. “You have my full support.”

Gretchen Whitmer, governor, Michigan

Michigan Governor Gretchen Whitmer has built a strong base in the closely contested state of Michigan, running on a platform of straight talk and kitchen-table issues. She attracted Biden’s attention in 2020, being vetted as a possible running mate before Biden picked Harris.

She was a top supporter of and spokesperson for Biden’s reelection bid. A Harris-Whitmer ticket would be the first all-woman ticket for a major US political party a potential bonus in an election where women’s reproductive rights are a top issue, if such a pairing could surmount any sexism.

Whitmer endorsed Harris in a social media post on Monday and said she will serve as co-chair of Harris’ campaign.

She told CBS affiliate WLNS that she would not take the vice presidential post if offered, saying “I am not leaving Michigan.” Harris will focus on lowering costs for Michigan voters, “restoring their freedoms, bringing jobs and supply chains back home from overseas, and building an economy that works for working people,” Whitmer said in a separate statement.

“We cannot let Donald Trump anywhere near the White House. Let’s go!”