WESTERVILLE, Ohio — In the last few days, Joseph R. Biden Jr. has unveiled a new government ethics plan and vowed that his family members would do no business overseas during a Biden presidency. His son, Hunter Biden, said he would step down from his role with a Chinese investment firm, and sat for his first television interview of the campaign. And in Iowa, the elder Mr. Biden delivered a fist-pounding diatribe against President Trump, casting him as the embodiment of public corruption.
Altogether, it has added up to the most assertive attempt by Mr. Biden and his camp to extinguish questions about his son’s business activities since Mr. Trump began raising them as a campaign issue, often in false or exaggerated terms.
What remains to be seen is whether Mr. Biden can put those issues to rest on a far bigger stage — at the CNN/New York Times Democratic primary debate in central Ohio on Tuesday night.
As fierce as Mr. Biden’s efforts have been since the start of the weekend, he has in some ways raised as many questions as he has answered. If his family intends to shun foreign business in the event that he becomes president — as Hunter Biden said he would on Sunday — voters may wonder why they didn’t do it far sooner, when Mr. Biden was conducting foreign diplomacy as vice president.
Perhaps most of all, anxious Democratic leaders are looking to the former vice president for a sign on the debate stage that all of this is not coming too late in this campaign to make a difference — to quash the undercurrent of doubt among some Democratic strategists, activists, donors and voters that Mr. Biden is really ready for a general-election fight against a president prepared to scorch and smear his way to a second term.
“I’m a little worried about how Joe’s going to do if he were to get on a debate stage with the president, a little worried he’d be able to get him rattled,” said Tom Courtney, the co-chairman of the Des Moines County Democrats in Iowa, a state where the Biden campaign has made substantial investments. “I would like to see him quit getting bogged down in little things. This guy has got way more experience than all the other candidates up there. He needs to take charge and show that.”
Mr. Biden is hardly the only candidate who faces high stakes in Tuesday’s debate. Senator Bernie Sanders, 78, the oldest candidate in the race, suffered a heart attack. He now faces significant questions about his age and stamina at a moment when he consistently trails Mr. Biden and Senator Elizabeth Warren in many national polls. Ms. Warren, a new front-runner, is all but certain to confront more scrutiny from other candidates onstage, which would put to the test her ability to weather sharper criticism in the national spotlight.
But no one among the 12 candidates in the debate has faced as many challenges as Mr. Biden — some of them self-inflicted, and some created by a president in full attack mode, seizing on Hunter Biden’s overseas business dealings in an attempt to tarnish the former vice president. After responding tentatively at first, Mr. Biden has steadily increased his counterattacks against Mr. Trump.
Mr. Biden himself has pledged to be more assertive in Tuesday’s debate, acknowledging at a fund-raiser last week that “I’ve got to be more aggressive” and adding, “I’m not complaining, I’m a big boy.”
“When he says, ‘I’m going to be more forceful and active on the stage,’ I think he means he’s not going to let people misrepresent his record, and in particular, he’s going to take it to Trump because I think he’s had enough,” said Senator Chris Coons, Democrat of Delaware and a Biden ally.
Mr. Biden enters the debate having endured perhaps the worst month of his candidacy, a period defined by his slow and halting pushback against Mr. Trump — a hesitancy some early-state Democratic voters have noticed — and a time-consuming scramble for campaign donations at the end of a less than commanding fund-raising quarter. Mr. Biden is more reliant on high-dollar fund-raisers than his leading rivals, a requirement that took him largely out of public view for days, just as Mr. Trump was amplifying his false claims about Hunter Biden’s business dealings overseas.
Steve Snyder, a college professor from Des Moines, expressed respect for Mr. Biden as he waited for Mayor Pete Buttigieg of South Bend, Ind., to address a shivering crowd gathered outside a Des Moines high school on Saturday night. But, noting the pace of the president’s broadsides against Mr. Biden, he said that the Biden campaign appeared to be “slow-footing” their response, even as he acknowledged the challenges of responding to Mr. Trump.
“This isn’t a typical campaign,” said Mr. Snyder, who said he is leaning toward supporting Ms. Warren. “This is information warfare. They’re just not responding quick enough.”
Asked to address concerns that Mr. Biden’s message was getting drowned out, a view which was shared by some other Iowa voters, Mr. Biden’s campaign spokesman, T.J. Ducklo, said in a statement Sunday that Mr. Biden “will continue punching back hard against Donald Trump’s pathetic and increasingly unhinged behavior, while also keeping the focus on issues where Trump has failed middle class families, like rising health care costs and the urgent climate crisis.”
He also cited Mr. Biden’s standing in recent polls, arguing that “these attacks aren’t working with Democratic voters.” Mr. Biden’s numbers have generally remained steady at the national level since the controversy over Ukraine broke open last month.
Yet Mr. Biden, who months ago held a commanding edge over his rivals, has nearly lost his lead in primary polls, having dipped well below 30 percent in The New York Times national polling average. He is barely ahead of Ms. Warren in that ranking, which gauges national support, and he is tied with her, or trailing, in three of the four early-voting states. While Mr. Biden maintains a powerful bloc of support in the race, built on the loyalty of African-American voters and moderate whites, that coalition has been shrinking rather than growing — a trend he must reverse if he is to become the nominee.
Mr. Biden raised $15.2 million in the third quarter, a sturdy sum but far less than what Mr. Sanders and Ms. Warren collected. He also trails Mr. Buttigieg, who has become a cause célèbre for many party donors.
And Mr. Biden has declined to reveal how much money he had in the bank at the end of September, raising concerns among his supporters that he may not have the cash reserves required to defend his dwindling lead. He is legally required to disclose that figure by the end of Tuesday, a coincidence that makes the evening of the debate a moment of truth for his campaign in more ways than one.
The debate, his allies acknowledge, is perhaps his best chance to reassure his supporters and regain some momentum in the race. That would likely require a feat Mr. Biden has not accomplished so far in this race: a thoroughly forceful debate performance, free of missteps or flustered responses to predictable criticism from his Democratic opponents.–
“He needs to figure out how he wants to handle all this Trump noise,” said Jeff Link, a veteran Iowa Democratic strategist. “He’s got to find a way to basically say to the audience, ‘There’s only one guy that Trump is worried about and is attacking, and let me tell you what I’m going to do about it.’”