SALEM, New Hampshire — Joe Biden said Senate Republican calls for him as a witness in President Trump's Senate impeachment trial reflects the strength of his Democratic presidential bid. But his supporters aren't so sure.

The former vice president has for weeks faced demands by GOP senators that if Trump administration officials have to testify, so should he, and possibly his son, Hunter Biden, who worked for a Ukrainian natural gas company while his father oversaw U.S. policy toward that country. Trump’s allies continue to repeat conspiracy theories that Joe Biden leveraged his position as vice president to help his son’s interests.

Biden, 77, has tried to spin the attacks into a positive and proof that he is the strongest candidate to take on Trump.

“I’m wondering why he doesn’t want to run against me. What do you think?” Biden said in Salem, New Hampshire, on Saturday. The crowd of more than 300 laughed.

Undecided voters, however, are not convinced that Biden will be able to withstand a barrage of attacks from Trump in a general election. The memory of Hillary Clinton’s candidacy being derailed by Trump’s unpredictable tactics in 2016 is still fresh, and Republican fixation on the Bidens through the impeachment trial amplifies his vulnerabilities.

“Let’s say he becomes the nominee. How is he going to fight against the dirty tricks of Donald Trump?” said Sally Hamblen, 65, a risk management professional from northeast Massachusetts.

Gary Tallman, an attorney and undecided voter from Randolph, Vermont, said he drove two hours to see what Biden would say about how he would stand up to Trump’s attacks. “That's what I want as part of the reason I want to see him,” said Tallman, 53.

With one week until the first-in-the-nation Iowa caucuses and two weeks until the New Hampshire primary, poll after poll shows that most likely Democratic primary voters prefer a candidate that can beat Trump over one they agree with more on policy issues. Doubts that Biden can withstand attacks from Trump rebut Biden’s core electability argument.

Rival candidates have indirectly swiped at Biden’s judgment when confronted with questions about Hunter Biden joining the board of Ukrainian gas company Burisma, saying that they would not want their vice president’s son or daughter to serve on a foreign company’s board. They have defended him, though, against the suggestion that Biden conditioned $1 billion in loans to Ukraine on firing Ukrainian prosecutor Viktor Shokin because Shokin opened an investigation into Burisma.

When asked about the issue, Biden states little more than that his son did nothing wrong and that no credible outlet or individual has said he did anything wrong. In December, a video of Biden answering a question about Ukraine and Hunter Biden from an independent Iowa voter went viral. Biden called him “a damn liar.”

“I worry about Biden, specifically when under pressure; it doesn't seem like he's always the smoothest. So, I would hate for that to impact any chances,” Manchester, New Hampshire, banking professional Julie Polenchar, 35, said of Republican attacks on the Biden family’s connection to Ukraine.

Though he is not the nominee, the Democratic National Committee is already working to defend Biden from Republican attacks more directly than Biden defends himself. The party's "war room" sent an email on Monday with talking points, noting that "everyone, not just Biden, wanted Shokin gone" and that "Shokin was fired not because he wanted to investigate Burisma but because he didn’t want to investigate anything."

Stephan Rodriguez, 30, went to Biden’s event to ask about Biden’s media strategy, worried that the former vice president is not prepared to spin the media narrative in his favor and face Trump’s army of rabid online followers.

“That's what Trump did, and that's what Obama did. They got the media attention and then connected it to Twitter and social media and the grassroots," said Rodriguez, a nonprofit professional from Lincoln, Rhode Island. While Trump and his allies effectively “weaponize” memes — “You'll see a meme of Joe Biden doing something silly, and you'll laugh” — Biden “doesn't do that,” he said.



Stephan Rodriguez displays a "crystal" he hoped to give Joe Biden in Salem, New Hampshire. (Emily Larsen/Washington Examiner)

Rodriguez pulled out a small inch-long clear stone from his pocket. “I also want to give him my crystal,” he said. “I literally pray to God that he gets elected or that the right person gets elected, because, if not, we’re screwed.”

Biden did not take any audience questions after his speech, but Rodriguez was able to ask his question as the former vice president greeted attendees and took selfies.

“It was a terrible answer. His answer was, ‘Yes, I'm your guy,’ basically,” Rodriguez said. “I don’t think he listens to his staffers. I think his staffers notice that marketing or public relations and media relations are the skills that you need to work to navigate this campaign. He doesn't have those things.”

Concerns about Republican attacks negatively affecting Biden came up on Monday at an event for former South Bend, Indiana, Mayor Pete Buttigieg in Boone, Iowa. "I'm just afraid — son of the Vice President Biden's gonna be taken out of the contest by the impeachment trial if they — if the Republicans keep pushing this Ukraine tie," said Bob Getschman, 65, who is retired.

Tallman, the Vermont voter who saw Biden in Salem, is still undecided on who to vote for but left the Biden event with a positive impression. “It makes me feel a little better,” he said. “We’ll see, though.”

The Massachusetts risk management professional hoped that Trump’s negative attacks could make voters sympathetic to Biden. “Some people might say they're sick of the dirty tricks,” Hamblen said.

Naomi Lim contributed to this story.