Republicans' white Catholic vote now flocking to Clinton
At the start of the month, Donald Trump led Hillary Clinton by 56-31pc among white Catholics.
According to the latest poll, in the wake of the lewd video and sexual assault allegations against Mr Trump, Mrs Clinton has taken a 46-42pc lead.
Overall, the Catholic vote is 61-34 in her favour.
What ever happened in last night's final debate in Las Vegas, this is a major blow to Mr Trump's chances of pulling off a victory in three weeks' time - in fact it could even be fatal.
White Catholic support has been crucial to Republican presidential hopefuls for decades and helped the party make sweeping gains in the midterm elections of 2010 and 2014.
Mitt Romney secured 59pc of the white Catholic vote in 2012.
"That's not where Trump wants to be in the homestretch, particularly with a core constituency in Mid Western battleground states," Robert Jones, a Public Religion Research Institute pollster, told the 'New York Times'.
Aside from the disclosures this month about Mr Trump's sexually aggressive language towards women and alleged history of assault, which the candidate denies, his spat with Pope Francis is unlikely to have helped his popularity among the demographic.
In February, the Pope claimed the Republican "is not a Christian" in response to a question about the billionaire's plans to deport 11 million illegal immigrants and build a wall on the US-Mexico border.
Mr Trump responded by calling the pontiff's attack on him "disgraceful".
It's not all plain sailing for the Clinton camp's hopes of sweeping up the white Catholic vote, however.
Emails released earlier this week showed senior campaign officials discussing Republican Catholics in offensive terms.
John Halpin, a senior fellow at the Centre for American Progress, a Democratic think-tank with close ties to the Clinton campaign and the Obama White House, wrote in 2011 that "the most powerful elements of the conservative movement are all Catholic" and described their positions as "an amazing bastardisation of the faith".
He added: "They must be attracted to the systematic thought and severely backwards gender relations and must be totally unaware of Christian democracy."
Republicans claimed that the emails highlighted the Clinton campaign's "breathtaking anti-Catholic bigotry".
Moreover, Tim Kaine's vocal support for abortion rights - despite his own Catholic faith - may put off some Catholic voters.
"Senator Kaine has said, 'My faith is central to everything I do'. But apparently, and unfortunately, his faith isn't central to his public, political life," Bishop Thomas Tobin, of the Diocese of Providence, said.
Mr Trump's problem with white Catholics mirrors his declining support among evangelical Christians following the release of the video in which he is filmed making sexually aggressive comments and talks about "grabbing (women) by the p****".
According to a Reuters/Ipsos opinion poll last week, Mr Trump had only a one-point edge over Mrs Clinton among people who identified as evangelicals, which was down from a massive 12-point advantage that the Republican held in July.
'Christianity Today', a leading evangelical magazine, said in an editorial that Christians should not support a man whose life is based around "idolatry, greed, and sexual immorality".
Bolstered by several opinion polls that have her leading in the key swing states, Mrs Clinton's campaign spoke bullishly earlier this week about making Democrat gains in traditional Republican states.
And last night she launched a historic bid to win the deeply Republican state of Texas.
Mrs Clinton committed $1.5m to start running television advertisements in the Lone Star state, which is usually ignored by Democratic presidential nominees.
It followed a poll by the University of Houston which put Mr Trump on 41pc support in the state, with Mrs Clinton at 38pc. Aides also said that Mrs Clinton would be "dramatically expanding" her campaigning in Arizona.
Michelle Obama, who has been a key weapon for the Clinton camp at both the convention and subsequent events, will speak in Phoenix today.
"Donald Trump is becoming more unhinged by the day, and that is increasing prospects for Democrats further down the ballot," Robby Mook, campaign manager said.
Indiana and Missouri - which have voted Republican for decades - are also being targeted as states where Democrats could make gains. (© Daily Telegraph London)