Vice President Joe Biden has spent the last six and a half years as the consummate example of a quiet VP. Taking after Al Gore as opposed to Dick Cheney, Biden has remained in the shadows, letting President Obama have the spotlight. Like many vice presidents, he has become a staple of late-night comedy monologues, and his loose way with phrasing gives them plenty of material to work with. Judging by his standalone popularity, he wouldn’t seem to pose much of a threat to Hillary Clinton. But as he apparently ponders a run at the big chair, polls show that Clinton has reason to be concerned.

According to a new poll from Quinnipiac University, Biden actually fares a bit better against Republican opposition than does Hillary. Matched head to head with Donald Trump, Biden wins 48 to 40 percent. Matched with Jeb Bush, he wins 45 to 39 percent. Clinton wins against these candidates as well, but the margins are tighter. She leads Trump by 4 percent and Bush by 2.

Matched against each other, Clinton still enjoys a mild lead over Biden. Then again, Biden has not declared his candidacy. And even as the vice president of the United States, he doesn’t enjoy the kind of mainstream recognition as the former secretary of state. If he chooses to run, the polls could change in a hurry.

According to a report from POLITICO, former president Bill Clinton is deeply concerned about a Biden bid.

Clinton’s camp, hands full with the email controversy and a surprisingly stout challenge from independent Vermont Sen. Bernie Sanders, isn’t in a patient mood. Bill Clinton, according to a person who has spoken with the former president in the last couple of weeks, is “very agitated” by the possibility of a Biden candidacy and incensed at the press hype around a possible bid.

Publicly, Hillary is affecting a shrug. “He should have the space and the opportunity to decide what he wants to do,” she said Wednesday. “I’m going to be running for president regardless.”

Under ordinary circumstances, Hillary would have little to fear. But these aren’t ordinary circumstances. She is drowning in scandal, and even former supporters are starting to worry that there might actually be something to this whole email thing. Her favorability numbers are upside down, and the majority of voters see her as untrustworthy. It’s obvious that the DNC – to say nothing of Obama himself – is hedging its bets. Biden has something that Clinton lacks: namely, likability. If he can leverage that into a powerhouse campaign, Clinton’s White House aspirations could be doomed.