Campaigning in New Hampshire over the weekend, former Vice President and 2020 presidential candidate Joe Biden talked himself into another news cycle about his gaffes. He confused the first primary state for neighboring Vermont. Then he forgot where he had spoken on Dartmouth College’s campus just hours before.

“I want to be clear, I’m not going nuts,” he told reporters, according to the Los Angeles Times. “I’m not sure whether it was the medical school or where the hell I spoke. But it was on the campus.”

On some level, this is nothing new for Biden, who has a history of slipping up and saying things that are slightly off or need clarification. And it’s true that the grind of the campaign trail, which puts candidates on a tireless schedule between states and time zones with little downtime, can be brutal for anyone.

But Biden’s off-the-cuff, rough-around-the-edges brand is being seen through a new lens in this presidential primary for the Democratic nomination: his age.

“I am in my 70s and I know they are in their 70s, and I couldn’t handle that, no way,” Carol Rork, a 79-year-old resident of Britt, Iowa, told Vox after the Wing Ding dinner, where Biden spoke, in early August. An April poll from Reuters/Ipsos found more than half of Democrats were less likely to support a presidential candidate over age 70.

Biden’s campaign chalks it up to a press hungry for a juicy headline. Biden himself has attributed the coverage of his gaffes to his frontrunner status; he has held a comfortable lead in early polls ever since jumping into the race, according to the RealClearPolitics polling average. That said, his campaign is acknowledging the narrative; the campaign tweeted a video in which an Iowa voter told Biden that his “fiery” speech quelled any initial concerns she had about his age.

Biden, at 76, isn’t the oldest candidate in the current field (that distinction goes to Bernie Sanders, who will be 79 by Election Day 2020) — but voters are increasingly questioning how old is too old to be president.

Voters are wondering aloud if Biden is too old

Biden’s age comes up with voters on the campaign trail. Numerous voters in Iowa and New Hampshire told Vox “he’s too old” when asked whether they were considering Biden.

“I hate to say it, but you need someone younger. He’s my age.” Dawn Bassett, 72, of Kanawha, Iowa, said of Biden.

“I liked Biden as vice president, but Joe has seen his days. I think he’s too old,” Sarah Morris of Waterford, Vermont, said at an Elizabeth Warren event in New Hampshire.

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And while several recent polls have found Biden still in the lead — including a Morning Consult 2020 poll released Monday night, which showed him at 33 percent, a full 13 points ahead of Sanders, his closest challenger — a few other recent polls have shown the 2020 race turning into a three-way tie between Biden, Warren, and Sanders.

“It’s not an issue of numerical age, but it’s an issue of how you act and do you look like you’re up to the job, and that’s why you’re not hearing about Sanders,” said Monmouth University polling director Patrick Murray.

A February NBC/Wall Street Journal poll showed 62 percent of voters said they had “reservations” or were “very uncomfortable” voting for a candidate over the age of 75. And a Pew Research Center poll conducted in May showed just 3 percent of Democrats and Democratic-leaning independents saying the 70s are the best age for a president (it’s worth noting that Biden, Sanders, and Warren are all in their 70s).

The Biden campaign is seemingly aware of this concern; they recently released a video on Twitter of him talking to an unnamed Iowa voter, who tells Biden she wants to vote for a presidential candidate younger than she is — but “when you got to the passionate fiery part of your speech, I stopped worrying,” she says in the video.

We have to remember who we are — this is the United States of America. There is not a single thing we cannot do if we do it together. pic.twitter.com/ALa3yqf2GD — Joe Biden (@JoeBiden) August 24, 2019

Other voters aren’t so sure.

“I don’t think he can take on Trump for that reason. I don’t think Biden is quick enough and sharp enough to take him on,” Campton, New Hampshire, voter Lizzy Berube told Vox at a recent Warren event in New Hampshire. “His story is incredible, but he’s just too old.”

Frequent news about Biden’s gaffes has fueled these fears among voters in the key early states of Iowa and New Hampshire, especially as voters consider a potential general election matchup between the former vice president and Trump, who has already bestowed Biden with the nickname “Sleepy Joe.”

Others concerned with Biden’s age said it had less to do with gaffes than with the perception that Biden is out of touch with the current Democratic Party because he is staunchly moderate and has some controversial past votes on racial issues. (Of course, it’s worth noting that close to 40 percent of Democrats identify as moderates.)

“Initially I really liked him but his actions and his voting history tainted [that],” said Kacey Marsh of Whitefield, New Hampshire, who is supporting the 77-year-old Sanders. Marsh said she didn’t think age mattered too much, adding, “Age is a number; it’s relative.”

“I really don’t want to vote for Biden,” said a younger voter, Rory O’Neil of Nashua, New Hampshire. “I don’t like his blanket non-apologies. I think Biden represents old moderate Democratic norms.”

Many voters told Vox that Biden’s years of experience in Washington could be considered an argument in favor of electing him president.

“He’s a creature of Washington — he has loads and loads of experience,” said Colebrook, New Hampshire, voter John Jolles. But he echoed other voters’ concern that Biden’s age could also be considered an electoral weakness.

Biden’s gaffes have been front and center

Biden has always been known for going off the cuff and saying things that get him into trouble.

During his short-lived 2008 presidential campaign, Biden famously called Barack Obama “the first mainstream African American who is articulate and bright and clean and a nice-looking guy.” Biden later apologized for the remark and would eventually go on to be Obama’s running mate. The same year, he asked a paraplegic, wheelchair-using state senator from Missouri to “stand up” at a campaign rally. And in 2012, Biden told an audience of mostly black voters that the Republican Party would “put them in chains.”

But recently, another narrative has come to define his campaign: a series of misspeaks and controversial comments that have raised questions about the possible effects of his age.

There was the time he waxed nostalgic about working with segregationist senators during his early days in the Senate, which California Sen. Kamala Harris weaponized against him in the first Democratic debate — one of the few times he saw a dip in the polls.

Biden has repeatedly referred to former British Prime Minister Theresa May as the late Margaret Thatcher. He said he met with school shooting survivors from Parkland, Florida, as vice president, though the shooting happened in 2018, well after Biden left office. After the recent mass shootings in El Paso, Texas, and Dayton, Ohio, Biden appeared to mix up those locations, before he caught himself.

Gaffes have always been part of Biden’s public image, well before this latest presidential run. His unscripted nature is a big part of his political persona, and he’s had a habit of making news for a slip of the tongue in years past. The big difference now is that Biden is the frontrunner for the Democratic nomination for president, with each misspeak front and center.

So far, the gaffes haven’t sunk him in the polls. He has sat somewhat comfortably in the lead, 10 points ahead of the rest of the field in the polling average. But recent polls have shown the primary looking increasingly like a three-way race between him, Sanders, and Warren, who have their own electability hurdles. Sanders is also getting questions about age; during a recent swing through New Hampshire, one voter directly asked him about the fact that he’s nearing 80 years, and about his health.

As voters continue to prioritize “electability” — or the ability to beat Trump — each slip-up is getting scrutinized heavily.

“He’s making more unforced errors than Sanders has,” said University of New Hampshire pollster Andy Smith of Biden. “If Biden’s message is ‘I’m electable,’ you have to be able to demonstrate that. He’s given supporters cause to be concerned and given opponents an opportunity to go after him.”

Electability is the entirety of Biden’s message

Biden’s candidacy is based on the premise that he’s the most electable candidate. The big question is whether voters’ concerns about age will cut into his support down the line.

At a separate recent campaign stop in New Hampshire, Biden’s wife, Dr. Jill Biden, flat-out told voters they should consider her husband because he had the best chance to beat Trump.

“I know that not all of you are committed to my husband, and I respect that, but I want you to think about your candidate, his or her electability, and who’s going to win this race,” she said. “You know you may like another candidate better but you have to look at who’s going to win. Joe is that person.”

Unlike Warren (the plans candidate) and Sanders (the political revolution candidate), the biggest part of Biden’s pitch to voters is that he has the best shot of unseating Trump in a general election and returning America to the normalcy it enjoyed in the pre-Trump era that Biden, as Obama’s vice president, embodies.

This political message may be all the more salient considering Sanders and Warren are Biden’s biggest competition right now, and both are seen as considerably more progressive than him. But Biden’s electability message also has an inherent weakness: If voters start thinking he’s not as electable as he says he is, his pitch sounds hollow.

“The moment he’s shown not to be electable, since they have no other reason to be attached to Joe Biden, it’s easy to move these voters to someone else, at least temporarily,” Murray, the Monmouth pollster, told Vox.

It’s a feedback loop that can be seen in a Monmouth University poll released Monday that found a three-way tie between Biden, Sanders, and Warren (a necessary caveat about this poll is its small sample size). The Monmouth poll showed Biden’s support had dropped among moderate and conservative-leaning voters, who redistributed themselves fairly evenly among Sanders and Warren. That’s in part owing to voters starting to pay attention to media coverage, which these days includes a fair amount of Biden’s gaffes, Murray told Vox.

Biden’s early support has “been built [with] name recognition among voters who have not been paying a lot of attention,” Murray told Vox. “As support for Biden seems to be getting shakier, they’re looking around for another name that they know.”