Donald Trump has unleashed a torrent of Twitter attacks on the party he hopes to lead to the White House, threatening to plunge Republicans into an all-out conflict with just four weeks remaining until the US general election.
Declaring himself unshackled, the billionaire businessman went after House Speaker Paul Ryan after the congressional leader effectively abandoned Mr Trump in a private call with fellow Republicans.
The series of Twitter posts appeared designed to stem the flow of Republicans who have said they will not vote for Mr Trump or have urged him to exit the race since last week's release of a tape showing him using predatory language regarding women.
Disloyal Republicans "are far more difficult" than Democrat Hillary Clinton, Mr Trump said.
"They come at you from all sides," he tweeted. "They don't know how to win - I will teach them!"
According to people on Monday's telephone conference call, Mr Ryan said he would no longer campaign with Mr Trump, focusing instead on ensuring Mrs Clinton doesn't get a "blank cheque" with a Democratic-controlled Congress.
Mr Ryan received both support and criticism from House members, reflecting Republicans' disunity and the disarray of their election strategy with less than a month to go.
Assailing Mr Ryan, Mr Trump said members "went wild" at the disloyalty of the "very weak and ineffective" speaker.
"It is hard to do well when Paul Ryan and others give zero support!" Mr Trump tweeted, declaring inaccurately that every poll had him winning the weekend's second presidential debate against Mrs Clinton.
One tweet complained that Democrats are "far more loyal to each other than the Republicans!" Another was celebratory: "It is so nice that the shackles have been taken off me and I can now fight for America the way I want to."
While Mr Trump's candidacy has long exposed the party's divisions, Republican leaders had hoped to prevent an all-out civil war until after the election. But House and Senate candidates fear Mr Trump's 2005 comments about women will drag down their own electoral prospects, if not stain the Republican brand for a generation. Others see no way for Republicans in some races to win without the backing of Mr Trump's loyal supporters.
Brendan Buck, Mr Ryan's spokesman, offered a muted response to Mr Trump.
Mr Ryan is "focusing the next month on defeating Democrats and all Republicans running for office should probably do the same," he said.
Forty Republican senators and congressmen have revoked their support for Mr Trump - with nearly 30 of them urging him to quit the race altogether. Few of these were ever passionate Trump supporters. The head of the Republican National Committee has stuck by the Republican nominee, declaring his full coordination with Mr Trump's embattled campaign.
Mr Trump apologised during Sunday's debate but also dismissed his comments about groping women without their permission as merely "locker room talk". The explanation failed to end the controversy, and Mr Trump's attacks on Mr Ryan threatened to distract from what Republicans want to be his main message: Going after Mrs Clinton.
The Democratic nominee, for her part, touted new ideas on Tuesday to provide tax relief for families with young children. Her plan would double the Child Tax Credit and provide low-income families more money in refunds.
The "new tax credit will make their lives a little bit easier and help restore fairness to our economy," she said.
Mrs Clinton's focus on families came as her campaign grappled with newly leaked emails shedding more light on the interplay among the former secretary of state's family, her husband's business relationships and her presidential ambitions.
The emails posted by WikiLeaks detail concern about former Bill Clinton aide Doug Band and the private corporate advisory firm he co-founded.
Daughter Chelsea Clinton in 2011 forwarded a news article about money Bill Clinton was receiving through Mr Band's company and expressed alarm with its representatives calling British parliamentarians "on behalf of President Clinton" without her father's knowledge. Mr Band tells John Podesta, Mrs Clinton's campaign chairman, that Chelsea "is acting like a spoiled brat kid" because she hasn't found her way in life.
WikiLeaks says the messages come from Mr Podesta's accounts. Mr Podesta has said messages may have been altered or edited to damage Mrs Clinton. It is not clear who hacked Mr Podesta's emails. Last week, US intelligence officials blamed Russia's government for a series of breaches and leaks intended to influence the presidential election.
Mr Ryan's pressing goal over the next month is preventing Republicans from losing control of the House, a scenario that seemed remote just a week ago. They hold a wide 246-186 seat majority.