Who would be Hillary Clinton's running mate should she become the Democratic presidential nominee? Nobody knows, but some party leaders have already begun lining up behind a prospective candidate: Secretary of Labor Tom Perez.

Sen. Elizabeth Warren, D-Mass., herself a fan favorite for vice president, has even declared her support for Perez, who is admired by Democratic leaders but little known to the general public. Politico reported Monday that Warren put his name forward in a conversation on the House floor last fall. As a group of lawmakers casually discussed whom Clinton might pick for veep, the senator chimed in. "Oh, you'd be great, Tom," Warren reportedly said.

Perez's name has increasingly come up in recent weeks as Clinton has cemented her lead over her rival, Vermont Sen. Bernie Sanders, in the Democratic primaries. Perez endorsed the former secretary of state in December and "seems to have the most potential to appeal to the left flank of the party," according to Yahoo.

Perez, whose parents were Dominican immigrants, has served as a county councilman, secretary of Maryland's Department of Labor, Licensing and Regulation, assistant attorney general for civil rights in the Justice Department, and director of the Office of Civil Rights, according to his official biography page. Perez, 54, became labor secretary in 2013.

Perez has campaigned alongside Clinton in recent weeks, feeding speculation that he could become her VP pick. Clinton has said she and her peers "are so enthusiastic about him and what he's doing and what he stands for," Rolling Stone reported.

"To me you want somebody who can excite the Democratic Party, and he is a guy who can do it. He’s a great speaker and he happens to be Hispanic,” former Rep. Tony Coelho of California told Politico. “I think he’s ideal in every way for her."

Many Democratic voters have expressed hope that Warren would team up with Clinton, but the senator so far has declined to endorse a presidential candidate. Warren, a progressive, came under fire from Sanders supporters earlier this month for not supporting him in her state's primary, which Clinton won narrowly.