By Harper Neidig and Jonathan Easley - 10-08-16 13:45 PM EDT
Donald Trump's presidential campaign is teetering on the edge of implosion over the obscene sexual comments he made about women, with the nominee facing unprecedented calls from Republicans to drop out of the race.
Trump's late-night apology for the remarks failed to quell the storm over his comments, which were caught on video in 2005 and include a graphic line about grabbing women "by the p---y."
The political fallout snowballed on Trump on Saturday, one day before a pivotal second presidential debate against Democrat Hillary Clinton that is expected to draw tens of millions of viewers.
Republicans in the House and Senate are abandoning Trump in droves, with many retracting their endorsements or urging him to leave the ticket altogether for the good of the party.
Sen. John Thune (R-S.D.), the third ranking Republican in the Senate, on Saturday became the latest GOP official to call on Trump to withdraw.
"Mike Pence should be our nominee effective immediately," Thune tweeted.
The exploding controversy has thrown Republicans up and down the ballot into crisis mode and has put party in a desperate position as it seeks to maintain its majority in the Senate just one month before Election Day.
"I can no longer look past this pattern of behavior and inappropriate comments from Donald Trump," Rep. Joe Heck (R-Nev.), who is in a tight race for Nevada Senate, told supporters at a rally with Mitt Romney on Saturday. "My wife, my daughters, my mother, my sister and all women deserve better. The American people deserve better."
Trump has been defiant in the face of growing calls for him to step aside, saying there is "zero chance" that he will back out of the race.
"I'd never withdraw," Trump said in an interview with the Washington Post. "I've never withdrawn in my life. No, I'm not quitting this race. I have tremendous support."
Instead, Trump is vowing to redouble his attacks against Clinton for the way she treated the women who had affairs with Bill Clinton or accused him of sexual assault - a course of action Republicans have warned him against.
The seismic controversy has thrust Pence into a difficult spot.
The vice presidential candidate rebuked his running mate on Saturday, and said he is praying for Trump and his family during this difficult time.
"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 said in a statement. "I do not condone his remarks and cannot defend them."
Pence said he looks forward to Trump taking the opportunity at Sunday night's debate to "show what is in his heart."
The Indiana governor had tentatively planned to replace Trump at a joint appearance with Speaker Paul Ryan (R-Wis.) at a campaign event in Wisconsin on Saturday, but has pulled out at the last minute.
Ryan was scheduled to make his campaign appearance with Trump at an event meant to show party unity on Saturday, but he has disinvited the GOP nominee amid the uproar.
Ryan and other top GOP leaders in Congress are furious with Trump, both for his remarks and his handling of the fallout.
In the early hours following the breaking news, they made clear in a string of blistering statements that they did not believe Trump had adequately apologized.
Asked whether Ryan was swayed by Trump's apology, a source familiar with the Wisconsin Republican's thinking responded, "That's for the voters to decide."
"Mr. Trump said he plans to talk about this at the debate and so we'll see what more he has to say," added the source.
Some, such as Sen. Mark Kirk (R-Ill.), have called for Trump to be forcibly removed from the ticket, although it is likely too late to do so.
Rather, there will be growing calls for the Republican National Committee to pull its support for Trump and batten down the hatches around protecting the party's majorities in the House and Senate.
The RNC has so far swatted away speculation that it would consider cutting Trump loose.
Trump is running a bare-bones campaign that is overly reliant on staff from the RNC, and a reallocation of resources to down-ballot races would effectively doom his campaign.
Until then, down-ballot Republicans have begun signaling they'll be run parallel campaigns that are untethered from the GOP nominee; leaving the party in a terrible position just over a month before Election Day.
Vulnerable Republicans running for Senate - Sens. Kelly Ayotte (R-N.H.), Richard Burr (R-N.C.) and Mark Kirk (R-Ill.) among them - were quick to register their disgust with the party's nominee.
"I have reached the decision that I can no longer endorse Donald Trump," Idaho Sen. Mike Crapo said in a statement.