Hillary Clinton has pressed Republicans to take a clear stand on Donald Trump as she tries to capitalise on party divisions since revelation of his predatory comments about women prompted party leaders to abandon him.
The Democratic candidate's campaign manager, John Podesta, said that she will assert at campaign stops that Republicans - particularly those running for office in November - need to clarify their position on Mr Trump.
"Are they with him or are they against him?" Mr Podesta asked.
Mr Trump, meanwhile, highlighted a new batch of hacked Podesta emails published by WikiLeaks, the anti-secrecy group.
At a rally in Florida, he launched a fierce attack on Mrs Clinton and asserted that Mr Podesta's leaked emails show more clearly than ever that the former secretary of state and her family are corrupt.
"It never ends with these people," he said.
He condemned Mrs Clinton on a broad array of issues, including immigration, national defence and international relations, and asserted that official Washington - both Democrats and Republicans in Congress - is committed to protecting special interests rather than the people.
Mr Trump criticised the Justice Department's handling of the probe into Mrs Clinton's email server, claiming there was collusion with the Clintons, and he suggested that both Democrats and Republicans in Congress went along with it.
"Did they make a deal where everybody protects each other in Washington?" Mr Trump asked the crowd in Ocala.
Mr Podesta says the FBI is investigating Russia's possible involvement in the hacking of thousands of his personal emails, raising the extraordinary prospect of a link between Russia and the US presidential election.
Mr Podesta also said, without offering proof, that Mr Trump's campaign may have been aware of the hacking in advance.
While acknowledging the evidence was circumstantial, Mr Podesta said the alleged ties could be driven either by Mr Trump's policy positions, which at times echo the Kremlin, or the Republican's "deep engagement and ties with Russian interests in his business affairs".
Longtime Trump adviser Roger Stone flatly denied any such link to Russia, and senior Russian officials denied interfering in the election.
Russian president Vladimir Putin said in Moscow that "hysterics have been whipped up to distract the attention of the American people from the essence of what the hackers released ... For some reason nobody talks about this. They talk about who did it. Is it really that important?"
Previewing Mrs Clinton's planned rallies in Pueblo, Colorado, and Las Vegas, Mr Podesta said even those Republicans who have revoked their support for Mr Trump following revelation of his sexually aggressive comments have "propped him up for a very long time".
One such Republican, Senator Deb Fischer, of Nebraska, reversed herself and said she will support Mr Trump after all.
As party leaders step away from him, Mr Trump is vowing to win the election his own way.
He declared on Fox News on Tuesday night that he is "just tired of non-support" from Republican leaders and "I wouldn't want to be in a foxhole with a lot of these people".
With his campaign floundering and little time to steady it, Mr Trump is reverting to the combative, divisive strategy that propelled him to victory in the Republican primary.
That means attacking every critic - including fellow Republicans.
Those close to Mr Trump suggest it is "open season" on every detractor, regardless of party.
That approach raises questions about the future direction of the Republican Party.
Mr Trump's campaign manager, Kellyanne Conway, said she does not foresee a new political party emerging from the Trump split.
"What I think you do see is a party that has growing pains because it is an expansive party that represents different viewpoints," she said on Fox News.
"So I think this party is very dangerously close to being the party of the elites.
"And yet Donald Trump is really giving voice to the workers ... He's been able to expand the party in many ways."
Mr Trump is striking hard at House Speaker Paul Ryan, who told Republicans on Monday he will no longer campaign for Mr Trump with four weeks to go before Election Day.
"I don't want his support, I don't care about his support," Mr Trump said.
"I wouldn't want to be in a foxhole with a lot of these people, that I can tell you, including Ryan. By the way, including Ryan, especially Ryan."