“There’s nothing discernable to show Biden’s been punched in the nose over Ukraine,” said Tim Malloy, pollster with Quinnipiac University, which released a survey Tuesday showing Biden has lost no support from Democratic voters since its last poll released Sept. 25.

A Morning Consult poll released Monday evening also found the former vice president relatively untouched in the Democratic primary since the week before and sitting on 12-point lead over second-place Warren.

The reasons for Biden’s relatively stable survey numbers, pollsters and consultants say, are numerous: Democratic voters are naturally inclined to disbelieve any attack from Trump. It’s still too early to know if the accusations will gain traction. Attention is more focused on a president facing a looming impeachment than Biden. His Democratic rivals have also sidestepped the issue, or expressed their support for the former vice president in the face of Trump’s unsubstantiated claims.

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And Biden also appears to be more trusted by voters overall than Trump. An SSRS survey conducted for the Washington Post and released Tuesday reported that 60 percent believe Trump does not uphold adequate ethical standards while only 35 percent believe he does. In contrast, 47 percent believe Biden does uphold adequate ethical standards while 38 percent believe he does not.

An NBC/Wall Street Journal poll released Tuesday found that 53 percent believe Trump has not been honest and truthful in the Ukraine affair, while 38 percent believe he has.

“Americans filter these things through the messenger, the credibility of the messenger, and Trump is clearly lacking credibility,” said John Anzalone, Biden’s chief pollster.

Trump’s attacks on Biden — in public comments and on Twitter — have shown no signs of abating ever since the Ukraine news began to hit a major saturation point on Sept. 20 amid news the president was accused of improperly leveraging U.S. aid to the foreign government in return for it investigating the Bidens.

That news broke at a time when Biden’s poll numbers were sliding as Elizabeth Warren was starting to overtake him in some polls. Warren continues to lead Biden in some national polls, including the Quinnipiac survey.

But since Trump began ramping up his criticism of Biden — and since more news reports have surfaced revealing White House involvement in an effort to persuade Ukraine to investigate Biden and his son — the former vice president has held his own for the most part.

A Fox News poll in Wisconsin last week put Biden at 28 percent among Democratic primary voters — exactly what he had there in a Marquette University poll at the end of August.

The most recent Fox News poll in Biden’s South Carolina firewall, shows he has increased his support there 6 points since July and now tops the Democratic field with 41 percent of the vote.

“On a state level, it’s been a net plus over the last week. It helps further energize the volunteer base, it’s had a rallying around effect,” said Pete Kavanaugh, deputy campaign manager in charge of states for the Biden campaign. “Honestly, it’s safe to say we’ve seen a pretty significant uptick on what we’re able to do on the ground.”

Another adviser with the Biden campaign noted that non-stop coverage on cable networks has only given Biden loads of earned media attention while other competitors are either shut out from coverage or they’re trying to get a piece of the story by taking a stronger stance on impeachment or in defense of Biden.

While polling data suggests Biden remains largely untouched by Trump’s attacks among Democratic voters, the evidence is less clear among the general electorate. While Biden has led Trump in virtually every head-to-head match-up this year, his advantage over Trump has declined in at least one recent national poll.

Biden leads Trump by 9 points in Tuesday’s Quinnipiac survey — but that’s down from a 16-point edge in Quinnipiac’s late August survey.

Polls aside, at least one Biden donor says Trump’s focus on the former vice president is having a catalytic effect, at least for now, on Biden’s fundraising — which lagged behind his top-tier rivals in the recently-ended third quarter.

Joe Cotchett, a Bay Area donor who helped coordinate a Palo Alto fundraiser last week, said he had initially booked an intimate event for several dozen people. Once Ukraine started ramping up, he said his phone started ringing and ringing with more interest. The event, where tickets ranged from $1,500 to $10,000, ended up drawing close to 100 people.

“I’ve never seen so much interest in Joe,” Cotchett said. “Trump is getting his name out there every time he tweets. The theory is he’s the guy that Trump is worried about.”