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Could this be the poll Joe Biden was waiting for?

A new poll shows Biden stronger than Clinton against Republicans in 2016. Meanwhile, Trump expands his lead over Republicans.

In a finding sure to pour fuel on intense speculation about a potential Joe Biden presidential run, a new national poll suggests Biden could be a stronger general election pick than Hillary Clinton for Democrats. Meanwhile, the poll finds Donald Trump has expanded his lead over the rest of the Republican field.

Clinton continues to dominate the Democratic field, according to the new Quinnipiac University national survey, but her support has fallen from 55% a month ago to 45% today. Meanwhile, her top potential challengers have seen their support rise, with Sen. Bernie Sanders now at 22% and Biden, who is still deciding on a run, at 18%. No other candidate registers meaningful support, and 11% of Democrats remain undecided.

Related: Joe Biden weighs whether he has ‘emotional fuel’ to run

"Secretary Hillary Clinton continues her slide while Sen. Bernie Sanders continues to narrow the gap," said Tim Malloy, assistant director of the Quinnipiac University Poll. "But the real news is the man who isn't there -- yet. Vice President Joseph Biden has the best appeal in general election matchups against top Republicans.”

Biden has left the door open on a 2016 presidential run all year, but stepped up his examination of a run in recent days and taken concrete steps to explore a run.

"Note to Biden: They like you, they really like you, or they like you more than the others,” said Malloy. "If he is sitting on the fence, his scores in the matchups and his favorability ratings may compel him to say, 'Let's do this.'"

The survey finds Biden would beat leading Republican candidates Trump, Jeb Bush, and Marco Rubio by larger margins than Clinton or Sanders in hypothetical matchups.

Political scientists say early head-to-head polls are generally meaningless when it comes to predicting outcomes more than a year away. And Biden has been spared the GOP attacks and press scrutiny Clinton has endured for the past year, so his numbers would likely come down once he became a target.

But the poll will undoubtedly be seen by Biden allies as evidence of his strength and Clinton’s weakness, and has already been used by Republicans as a cudgel against Clinton.

The former secretary of state has made electability one of her top arguments when trying to win over Democrats, so findings like this one could damage her where it matters most.  

More troublingly, the poll finds Clinton’s popularity underwater with 51% giving her a negative favorability rating compared to just 39% rating her positively. That’s her worst ever in Quinnipiac’s polls. Biden is in the black with 48% giving him positive ratings compared to 39% saying the opposite.

And there’s more bad news for Clinton. “Liar" is the most common word that came to respondents’ minds when they were asked an open-ended question about the first thing they think of when thinking of Clinton. That was followed by “dishonest” and “untrustworthy,” before she finally gets better words like “experience” and “strong.” The poll included both Republicans and Democrats.

Related: Joe Biden's 2016 dreams: So close, and yet so far

"Arrogant" is that word most linked to Trump and while voters think of "Bush" when they think of Bush.

Clinton’s numbers have slumped under the weight of the controversy over her exclusive use of a private email server, and Democrats seem increasingly concerned it could hurt her general election prospects, even if they don’t have a problem with the email system themselves. An otherwise positive Suffolk University poll of Iowa Democrats this week found 52% worried the email issue could damage her against Republicans.

Meanwhile, on the Republican side, Trump “soars” to new heights, according to Malloy, while Bush continues to slip.

The poll finds Trump at 28%, up from 20% a month ago -- that’s the highest tally and widest margin for any Republican so far in this election. Ben Carson is next at 12%, beating Bush’s 7%, a number shared by Sen. Ted Cruz and Sen. Marco Rubio.

However, Trump also tops the "no way" list with more than a quarter of GOP respondents saying they would definitely not support him. Bush is not too far behind at 18%.