© Jordan Gale for The New York TimesFormer Vice President Joseph R. Biden Jr. delivers a speech at the Small Grand Things event center in West Point, Iowa.
WEST POINT, Iowa - Joseph R. Biden Jr. was making an impassioned case for protecting undocumented immigrants one recent Sunday when he abruptly stopped himself.
"There's many more things, but -" he said before trailing off.
Minutes later, Mr. Biden interrupted himself again.
"So there's a, there's - my time up?" he said, echoing a line he had used when he stumbled in the first presidential debate this year. "I guess not. I guess it is."
And as he spoke to reporters here last week about President Trump's freezing of military aid to Ukraine, he briefly fumbled his words.
"People are being killed in western, in eastern Afghan - excuse me, in eastern, uh, Ukraine," he said.
Six months into his presidential campaign, Mr. Biden is still delivering uneven performances on the debate stage and on the campaign trail in ways that can undermine his message. He takes circuitous routes to the ends of sentences, if he finishes them at all. He sometimes says the opposite of what he means ("I would eliminate the capital gains tax - I would raise the capital gains tax" he said in this month's debate). He has mixed up countries, cities and dates, embarked on off-message asides and sometimes he simply cuts himself off.
That choppy speaking style puts Mr. Biden at a disadvantage as his front-runner status erodes and he confronts growing pressure to expand his appeal with voters and donors. He faces intensifying competition for moderate support, a formidable liberal foe in Elizabeth Warren, attacks on his family by Mr. Trump and Republicans, and a troubling cash crunch.
At a time when he most needs to convey confidence and forcefulness, some Democrats say, he is instead getting in his own way.
"He does not do well speaking where he isn't giving a speech," said Chris Henning, the Democratic chair in Greene County, Iowa, who caucused for Mr. Biden when he ran for president in 2008. "He's not good in debates and he comes across like he's stumbling around, trying to figure out what he's going to say."
Mr. Biden's verbal miscues have long led to challenges. He was forced to withdraw from the 1988 presidential campaign after he presented biographical details from the life of the British Labour Party leader Neil Kinnock as his own. His gaffe-prone tendencies made national headlines during his 2008 presidential bid when he referred to Barack Obama as "the first mainstream African-American who is articulate and bright and clean."
But Mr. Biden can now appear less crisp, and more hesitant, than in the past - and also in comparison to more polished rivals in the crowded Democratic primary. As the early leader in 2020 polls he has spent more time in the national spotlight, and he is competing in a fast-moving social media environment in which gaffes are magnified and candidates are rewarded for being quick on their feet. © Jordan Gale for The New York TimesAn audience member listens as Mr. Biden speaks in West Point, Iowa.
Mr. Biden, 76, still leads many national polls, and he enjoys significant good will from many Democratic voters. Some attendees at his events in Iowa last week said Mr. Biden, who overcame a childhood stutter, is a relatable raconteur whose decades of experience are comforting amid the chaos of the Trump era. He can be forceful in denouncing the president from the podium, and is at his best in individual conversations with voters.
And of course, if Mr. Biden wins the nomination, he will face a president who is an undisciplined speaker in his own right - one who misstated the name of his own cabinet secretary recently, tortures grammar and spelling in his tweets and, most significantly, routinely makes false claims about matters large and small.
But Mr. Biden's inconsistent performances illustrate why many Democrats remain skeptical of his candidacy: Whatever his strengths in polls - and the data is mixed, especially in the early-voting primary states - on the ground his performances are often plainly shaky.
Nowhere are the stakes higher for Mr. Biden than in Iowa, the leadoff caucus state where Mr. Biden will return for a four-day swing on Wednesday. Ms. Warren has tied or moved ahead of Mr. Biden in some polls, and party officials on the ground say Mayor Pete Buttigieg of South Bend, Ind., appears capable of siphoning some of Mr. Biden's centrist support. Senator Amy Klobuchar, a moderate from neighboring Minnesota, also gained attention after the October debate. Last week, she qualified for the fifth debate, scheduled for next month.
While Mr. Biden's campaign has publicly sought to downplay expectations in Iowa, it has also invested heavily in both time and resources. In a confidential memo circulated last week, the campaign manager, Greg Schultz, said that Mr. Biden was positioned to have a "narrow advantage" in the state.
"I plan on winning Iowa. I'm working like hell to win Iowa," Mr. Biden told reporters here, adding, "It could end up being a must-win; it could not make a difference."
In Iowa and nationally, worries about Mr. Biden's speaking style are often intertwined with concerns about his age - though his allies and former staffers say he has long been prone to misspeaking.
Mr. Biden has said it is fair to raise his age, and in one of his stronger moments at the last debate, said that "with it comes wisdom." In a statement over the summer, his doctor said that he was in "excellent physical condition."
But several public appearances have intensified questions about his ability to connect in this political moment. At the September debate, Mr. Biden responded to a question about the legacy of slavery with a rambling answer that included advising the use of a record player to expose underprivileged children to more words. At a CNN forum focused on L.G.B.T.Q. issues this month, Mr. Biden - who was ahead of Mr. Obama in voicing support for same-sex marriage - still raised eyebrows for referencing "gay bath houses," while making a broader point about evolving attitudes.
"It doesn't necessarily bother me," said Steve Drahozal, the Democratic chairman in Dubuque County, Iowa, of Mr. Biden's "halting speaking style," allowing that Mr. Biden might simply be thoughtful. "But there are a lot of voters out there who want to be inspired by a candidate. Democrats win when we have an inspiring candidate."
Concerns about Mr. Biden's style aren't confined to members of the political class: Voters often raise the issue, including at his own events.
"I like Joe, but I don't think Joe's going to get it because he has not been doing very well with his speaking, with the debates," said Lisa Kane, 62, of Keokuk, Iowa, as she waited for Mr. Biden to speak. "Pete would do a better job. He's younger, a great speaker, he's smart, got the military background."
Debbie Hunter, who stood with Ms. Kane, based her assessment on Mr. Biden's debate performances, which many Democrats continue to see as lackluster at best.
"He's real hard to follow," Ms. Hunter, 57, said. "I have a lot of concern about his ability to concentrate, his attention span, the ability to get the job done."
But Patty Madden, 69, and Bev Alderson, 60, two former teachers, said Mr. Biden's informal, story-laden speaking style was part of his charm.
"I love it," Ms. Alderson said. "It appeals to the common people, working class, Americans, everybody!"
"I know he falls over some of his words, we all do," Ms. Madden said.
"Oh, big deal!" Ms. Alderson interjected. "He speaks from his heart."
At his two events in Iowa last Wednesday, Mr. Biden spoke, relatively carefully, from teleprompters. There were some apparent tangents - one promise to wrap up his address drifted into a digression on illness in China - but he also ended with a forceful conclusion about America's strengths and received a standing ovation.
Mr. Biden has also proven capable of speaking crisply and movingly, and he was a fierce competitor at the vice-presidential debate in 2012.
This year, too, he has had some electric moments, such as when he eviscerated Mr. Trump for fanning "the flames of white supremacy." And he can be sharper in exchanges with reporters than he is on a debate stage.
"His day after debate press conference have been outstanding," Jim Messina, Mr. Obama's 2012 campaign manager, wrote in an email. "He shines in that format, as he did in 2012. It also shows he still had a fastball. The mass format debates just aren't his strong suit. And that's probably O.K. The field is beginning to narrow. He still has time."
Some advisers and allies have said privately that they have little control over Mr. Biden's speaking style, but they also insist his debate performances have improved, and note that a string of controversies and wobbly public appearances have hardly crushed his campaign.
"Not one expert has been right about Joe Biden," said former Senator Barbara Boxer, a California Democrat and friend of Mr. Biden's. "It goes on and on. 'He can't make it, it's just the name ID.' Then he's going to fall out because he's too affectionate. Now he's going to fall down because he's too gaffe prone? Now it's the money? I just don't buy it."
In response to multiple questions for this article, a Biden campaign spokesman, Jamal Brown, pointed to steady poll numbers in head-to-head matchups with Mr. Trump, and to surveys that show him growing his support among Democratic voters.
Ms. Hunter, of Keokuk, said seeing Mr. Biden in person allayed some of her concerns and that she had moved him in her candidate rankings.
"If he wants to win these debates, he needs to speak up, get fired up," she said. Asked if he had done so in the event at West Point, she replied, "Well, a little. At the end."