NEW YORK/WASHINGTON (REUTERS) - US presidential nominee Donald Trump vowed on Saturday (Oct 8) to remain in the race even as his campaign was thrown into crisis as both his wife and running mate criticised him and more than a dozen prominent Republicans withdrew support and urged him to drop out following news of a recording of him making lewd comments in 2005.

Trump told the Wall Street Journal on Saturday morning "zero chance I'll quit."

Later, after meetings with his advisers, he tweeted: "The media and establishment want me out of the race so badly - I WILL NEVER DROP OUT OF THE RACE, WILL NEVER LET MY SUPPORTERS DOWN!"

He also told The Washington Post he may deliver a speech on Saturday afternoon to address concern among supporters and reiterate his determination to stay in the race.

The video was the latest calamity for Trump, who had hoped to revive his flagging campaign in the face of a recent drop in polls with less than a month until Election Day.

The 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. The video was taped only months after Trump married his third wife, Melania.

In a statement, Melania Trump called her husband's words "unacceptable and offensive to me."

"This does not represent the man that I know," Melania Trump said. "He has the heart and mind of a leader. I hope people will accept his apology, as I have, and focus on the important issues facing our nation and the world."

The backlash against the video was swift and widespread.

In an unusual move, vice-presidential running mate Mike Pence issued a critical statement, saying on Twitter that he cannot defend the nominee.

"As a husband and father, I was offended by the words and actions described by Donald Trump in the eleven-year-old video released yesterday," Pence, who is governor of Indiana, said in a statement. "I do not condone his remarks and cannot defend them."

Pence indicated he would continue to support Trump, despite calls from several Republicans that the New York real estate mogul step aside and let Pence be the nominee.

There is no precedent for a major party to replace its nominee this late in the campaign and it is unclear if there is an avenue to force him out. Voting has begun in several states, including the important swing states of Virginia and North Carolina.

A hastily recorded apology by Trump early on Saturday morning did not stymie an avalanche of calls from members of his party to quit.

Trump huddled on Saturday afternoon in Trump Tower with senior advisers, including New Jersey Governor Chris Christie and former New York City Mayor Rudy Giuliani.

Trump quickly moved to conduct damage control in Saturday's video in which he declared himself a changed man and attempted to shift the focus to his opponent, Democrat Hillary Clinton. He threatened, again, to focus his attacks on the infidelities of her husband, former President Bill Clinton, saying he would talk more about the pasts of both Clintons with only a month until the Nov 8 election.

Trump has dismissed questions about his own marital infidelities as irrelevant.

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

The video overshadowed the publication of excerpts of Clinton's paid closed-door speeches made public on Friday by a hacker who claimed to have obtained them from the e-mail account of John Podesta, the chairman of the Democrat's campaign.

In the speeches, she advocates for more open borders and trade, a position she abandoned during the primary because it was untenable to Democratic progressives. Trump has repeatedly criticised her for her past support of free trade.

COMMENTS CONDEMNED

Trump has struggled to win over women voters, and the video is expected to further feed Democratic criticism about his past behaviour towards women.

"I did try and f**k 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 p***y. You can do anything," Trump said.

House Speaker Paul Ryan disinvited Trump to a scheduled appearance on Saturday afternoon in Wisconsin.

Pence declined to speak in his place.

The list of Republicans announcing they would not vote for Trump or calling on him to step aside grew on Saturday: Senators Kelly Ayotte, Mark Kirk, Jeff Flake, John Thune, Mike Crapo, Shelley Moore Capito and Mike Lee; House members Jason Chaffetz, Mia Love, Joe Heck, Bradly Byrne, Martha Roby and Barbara Comstock; and Governors John Kasich, Dennis Daugaard and Gary Herbert.

Additionally, former presidential candidates Mitt Romney and Carly Fiorina also called on Trump to quit.

Capito, of West Virginia, called his remarks "disgusting and demeaning."

Chaffetz of Utah, one of Clinton's fiercest critics, 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 him.

Later in the day, Senator John McCain, a senior figure in the Republican Party who was its 2008 presidential nominee, formally withdrew his backing.

"I have wanted to support the candidate our party nominated. He was not my choice, but as a past nominee, I thought it important I respect the fact that Donald Trump won a majority of the delegates by the rules our party set. I thought I owed his supporters that deference," read a statement from McCain.

"But Donald Trump's behaviour this week, concluding with the disclosure of his demeaning comments about women and his boasts about sexual assaults, make it impossible to continue to offer even conditional support for his candidacy.

"Cindy and I will not vote for Donald Trump," he added, referring to his wife.

Other prominent Republicans, however, indicated they would stick with Trump.

Ralph Reed, head of the Faith and Freedom Coalition, and Tony Perkins, head of the conservative Family Research Council, said they would continue to support him.

Conservatives point to the fact that the winner of the November election will get to appoint a Supreme Court justice as reason to stick with Trump despite the video.

Greg Mueller, a conservative Republican strategist, pointed to Clinton's views on abortion as a reason religious voters will stick with Trump.

"Nothing indefensible that Donald Trump said 20 years ago is going to change that," he said. "Plus, to many religious voters, Mrs Clinton is the epitome of a corrupt politician."

Representative Jack Kingston, a Republican from Georgia, argued Trump has changed since the video was filmed. "I think 10 years ago he was a different man... I am very glad that he quickly apologised," Kingston said.