Exeter, New Hampshire (CNN) Joe Biden told voters in New Hampshire on Monday that he would consider choosing a Republican as a running mate, but added, "I can't think of one right now."

Biden discussed the possibility after a woman told the former vice president that if he is the nominee, he will "have to pull out all the stops."

"Our 21-year-old son said the other night, 'I wonder if Joe Biden would consider choosing a Republican as a running mate," the woman added.

"The answer is I would, but I can't think of one now," Biden replied. "Let me explain that. You know there's some really decent Republicans that are out there still, but here's the problem right now ... they've got to step up."

Over the past few months, Biden has offered several clues about who he might consider as his vice presidential pick if he earns the Democratic nomination. He previously said he would prefer to pick someone "of color and/or a different gender" as his potential running mate. Biden has also acknowledged he'd think about adding Sen. Kamala Harris of California and Sen. Elizabeth Warren of Massachusetts to his possible ticket.

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