NEW YORK/WASHINGTON: Republican presidential nominee Donald Trump scrambled to prevent his campaign from falling apart early on Saturday with a hastily prepared video statement expressing regret for making lewd comments about women.

Trump declared himself a changed man, but raised the infidelities of former President Bill Clinton and slammed his Democratic opponent in the November 8 election, Hillary Clinton, saying he would talk more about their past in coming days.

Disclosure of a 2005 video of Trump talking on an open microphone showed the then-reality TV star speaking openly about groping women and trying to seduce a married woman. Democrats have sought to highlight such behavior to prevent women voters from supporting him with less than a month to go until the election.

The video landed just ahead of the second presidential debate on Sunday night, which had been seen as critical for Trump to try to rebound from a dip in some opinion polls after a rocky performance in the first debate.

"This is nothing more than a distraction from the important issues we're facing today," he said, before turning to former President Bill Clinton's infidelities.

"We will discuss this more in the coming days. See you at the debate on Sunday," Trump said in his statement.

The bombshell development rocked Trump's campaign to its core and some Republican lawmakers disavowed him.

House of Representatives Speaker Paul Ryan withdrew an invitation for Trump to visit Wisconsin on Saturday and there were some calls for the New York businessman to step aside to let his vice presidential running mate, Mike Pence, become the party’s standard-bearer.

"Anyone who knows me knows these words don't reflect who I am. I said it, I was wrong, and I apologize," Trump said in his video statement, posted on his Facebook page.

Comments condemned

Trump's comments aired in a near-constant loop on US news programs on Friday.

"I did try and fuck her. She was married," Trump said about one woman, before discussing his attraction to others.

"I just start kissing them," he said. "And when you’re a star they let you do it."

"Grab them by the pussy. You can do anything," Trump said.

A stream of Republican leaders condemned Trump's lewd remarks, but a few lawmakers distanced themselves further.

US Representative Jason Chaffetz of Utah, who has been one of Clinton’s fiercest critics, said he had retracted his endorsement of Trump, telling CNN he would not be able to look his 15-year-old daughter in the eye if he voted for Trump.

Utah's Republican Governor Gary Herbert said on Twitter he would also no longer vote for Trump. "Tonight, millions of Republicans are facing a moment of truth," Herbert said.

Republican lawmaker Mike Coffman from Colorado told CBS that Trump should "step aside" and said "his defeat at this point seems almost certain."

Trump, known for his unconventional and controversial speaking style, has made a series of gaffes in his campaign but the graphic nature of the clip would hurt his standing among women, independents, and wavering Republicans, said David Yepsen, director of the Paul Simon Public Policy Institute at Southern Illinois University.

"We've never seen something like this Trump clip in a modern presidential campaign," Yepsen said, calling the incident "sad for the American political system" and for Trump's supporters.

Republican strategist Ron Bonjean said "this feels like it is quickly becoming a political 'game over'" for Trump.

"Unless voters don’t care about these issues or believe that this is simply political dirty tricks by releasing the videos now, Trump is going to have to pull a rabbit out of his hat in order to turn things around," Bonjean said.

Still, Trump's past controversial comments have failed to shake his core supporters, said David Axelrod, a former political adviser to Democratic President Barack Obama.

"Appalling as the (Trump) tape is, I'm reminded of all the times we have said, THIS time he's REALLY done," Axelrod said on Twitter.