CLEVELAND -- New Jersey Sen. Cory Booker is a finalist in Hillary Clinton's search for a running mate, a source familiar with the process confirmed Thursday.

Clinton is expected to choose her vice presidential nominee in the coming days, with the Democratic National Convention set to begin in Philadelphia Monday. Virginia Sen. Tim Kaine is widely seen as the front-runner, but Booker was also in the mix.

The Senate freshman and the former mayor of Newark already boasts a national profile and enthusiastic following. He would add a dose of energy and youthful appeal to the ticket and, as an African-American, would represent a key piece of Democrats' demographic coalition, but he is relatively inexperienced, particularly on the international stage.

In Cleveland Thursday to help counter the Republican National Convention, he deflected talk of being chosen.

"I'm here to talk about this convention," Booker told reporters. "I am very happy to do whatever I can to support this candidate."

Politico reported earlier Thursday that Booker had met with Clinton at her Washington home last week, and the Washington Post reported that he remained in the mix as Clinton, the presumptive Democratic nominee, considers a running mate.

Booker has traveled the country this year as a Clinton surrogate -- visiting 14 states -- and has rallied Democrats in battlegrounds such as Florida and Ohio, winning raves from the party faithful, though his work in Newark has also drawn criticism that the luster isn't matched by substance.

Booker, 47, has cultivated an image as a politician who focuses on positivity, a trait that might help counter the strongly negative perception many voters have of Clinton, who is widely seen as an entrenched part of Washington, and distrusted.

In recent days most of the talk in the vice presidential sweepstakes has centered on Kaine and agriculture secretary Tom Vilsack. Housing secretary Julian Castro and labor secretary Thomas Perez, both Hispanic, have also been prominently mentioned, as has Massachusetts Sen. Elizabeth Warren.

One complication if Booker is nominated: should Democrats win the White House, a Republican governor -- Chris Christie -- would appointed Booker's replacement in the Senate, potentially tilting the closely-divided chamber toward the GOP.

Booker said Thursday it has been difficult for him to watch the Republican convention and the rise of Donald Trump.

"This is now a counterfactual party that has no interest in discussing ideas and policies and facts," he said. "What really got me here was the level and intensity of the hate that I've seen on the floor and coming out of speakers."

He praised Clinton as "one of the smartest human beings I've ever met, one of the hardest working people in all of politics."

Booker is already scheduled to be a featured speaker at the Democratic convention next week, whether or not he is on the party's ticket.

Staff writer Maddie Hanna contributed to this report.

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