A newly fiery Joe Biden is shooting back at President Donald Trump for trafficking in debunked accusations about him and the Biden family, saying the president would not succeed in his efforts to "destroy" the Bidens.

"President Trump seemingly cannot tell the truth — about anything. He slanders anyone he sees as a threat. That is why is he is frantically pushing flat-out lies, debunked conspiracy theories and smears against me and my family, no doubt hoping to undermine my candidacy for the presidency," the former vice president and Democratic presidential candidate wrote in an op-ed in Monday's Washington Post.

"It's the same cynical playbook he returns to again and again. But this time, it won't work, because the American people know me — and they know him. I will put the integrity of my whole career in public service to this nation up against Trump's lack of integrity any day of the week," Biden wrote.

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Addressing Trump directly in his closing, Biden wrote: "Please know that I'm not going anywhere. You won't destroy me, and you won't destroy my family. And come November 2020, I intend to beat you like a drum."

Biden is now also fundraising off of Trump's attacks on his family, soliciting campaign cash for a "rapid response" to the president.

The missive reflects a newer, more aggressive pushback by Biden as Trump continues to advance unfounded allegations that Biden sought to get a Ukrainian prosecutor dismissed to protect his son, Hunter Biden, who had served on the board of a Ukrainian company once under investigation by the Ukrainian government.

Trump is now facing an impeachment inquiry — a process that is gaining support in polls — over charges that he made an investigation of the Bidens, and of interference in the 2016 campaign, a condition of sending congressionally-approved aid to a nation desperately trying to fend off Russian military aggression.

Biden had been relatively constrained when faced with the Trump attacks, frustrating some Democrats who thought Biden should fight back more aggressively. While Trump's accusations have been widely discredited, repeating that narrative over and over again can muddy the political waters.

Addressing the issue directly is a double-edged sword for Biden. Engaging with Trump on the issue continues the public discussion and could lead more people to consider the matter a legitimate complaint. But not slapping back means Trump is controlling the storyline.

Then-Sen. John Kerry, Democrat of Massachusetts, suffered from charges in his 2004 run for president that he exaggerated his Vietnam War record. Kerry – who earned a Bronze Star, a Silver Star and three Purple Hearts during his Vietnam service – was accused of embellishing his record by a group called "Swift Boat Veteran for Truth," and some felt he had waited too long to mount a full-throated self-defense.

The Biden op-ed is similar to a speech the former vice president delivered in Reno, Nev. last Wednesday, in which Biden slammed the "hatchet men" who repeat Trump's claims.

"He is repeatedly smearing me and my family. His party fans out to carry the smear," Biden said in Nevada. The speech occurred at night, West Coast time, and did not drive the day's campaign news.

After a strong start in a crowded Democratic primary field, Biden has begun to slip. He raised $15.2 million in the third quarter of this year, lagging behind not only Sens. Bernie Sanders of Vermont ($25.3 million) and Elizabeth Warren of Massachusetts ($24.6 million), but behind South Bend, Indiana Mayor Pete Buttigieg, who reported a $19.1 million haul.

Warren has been edging up as the biggest challenger to Biden, besting him for the first time in an Iowa caucuses poll in September .

But the vice president is still benefiting from a critical asset: a sense that he is more likely to achieve Democrats' central goal of ousting Trump.

A Fox News poll released Sunday showed Biden beating Trump in Wisconsin by 48% to 39% – outside the margin of error and dangerous news for Trump, whose wins in Wisconsin, Michigan and Pennsylvania were essential to his 2016 win. Warren and Sanders would also beat Trump, but by smaller margins (Sanders would win 45% to 40%, and Warren, 45% to 41%, the survey found).

The same poll had Biden dominating the Democratic primary field in both Wisconsin and in South Carolina, which is an early primary state. Biden takes 28% of the Democratic primary vote in Wisconsin, compared to 22% for Warren and 17% for Sanders.

In South Carolina, Biden gets 41% of the vote, compared to 12% for Warren and 10% for Sanders. Those numbers represent jumps from July for both Biden (who was at 35% in the summer) and Warren (who was at 5%).

Telling in both state polls is what motivates Democrats: getting Trump out of office.

Asked what was more important – electing the candidate they like best or defeating Trump – 52% of Wisconsin voters said it was more important to beat Trump, compared to 33% who think it is more important to nominate their preferred primary candidate.

In South Carolina, the results were similar, with 59% of Democratic primary voters saying getting rid of Trump will drive their primary vote decision, and 29% saying they would vote for the candidate they like most.

Trump's attacks on Biden could raise questions about Biden's ability to defeat Trump. But they also, Biden notes, show that it is the former vice president whom Trump fears facing next year.