Donald Trump. AP

Rep. Martha Roby is a three-term Republican congresswoman from deep-red Alabama.

She won her primary earlier this year with two-thirds of the GOP vote in a safely Republican district. She hails from the state where Sen. Jeff Sessions, one of Donald Trump's top surrogates, wields undue influence.

And, as of Saturday, she is no longer supporting Trump for president and is calling for him to drop out of the race.

"Donald Trump's behavior makes him unacceptable as a candidate for president," she said in a statement.

The deluge came fast and furious.

One by one, Republicans walked out on Trump, the dam broken by the more than decade-old, vile comments he made boasting about his sexual advances on women.

But amid the flood of unendorsements and the torrent of calls for Trump to step down, Roby's perhaps stood out the most. Donald Trump is on the verge of poisoning the Republican Party's brand for years, decades, even a generation — and the party knows it.

"Entirely possible. That has been the risk all along," said Matt Mackowiak, a GOP strategist and the founder of the Potomac Strategy Group. "... Picking up after the wreckage from potentially devastating losses in the Senate, House and governorships may take several election cycles."

There is a reason this Trump scandal feels different, and it is shown in the universal reactions of Republican leaders all the way up to House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell.

His comments should offend virtually everyone. Just about every single word uttered in the recording of Trump and Billy Bush, the television personality, is downright nasty toward women. Trump's immediate spin, that this was "locker-room banter," essentially suggested it was normal for all men to joke about sexual assault and cheating on your significant other.

If you are a parent, an aunt, an uncle (full disclosure), how can you allow a child to watch Sunday's debate descend into a level of vitriol that has never been seen in presidential politics?

This is the one that had Republicans rushing for the exits. With good reason: According to a source, a Democratic pollster in the field testing the down-ballot consequences of Trump's other recent controversies found little-to-no movement over the past few days.

Until Friday night.

As media coverage of Trump's lewd comments began to saturate the airwaves and internet, down-ballot Republicans in New York saw a sharp decline in support, this source said.

"We're f-----," said another source who works on the campaign of a Republican congressional candidate.

Republican National Committee Chairman Reince Priebus speaks in Washington Thomson Reuters

Four years ago, after a loss that seemingly pales in comparison to the potential in 2016, the Republican National Committee commissioned an "autopsy report."

The report was extensive, based on more than 2,500 interviews with voters, private-sector officials, and party members and elected officials, as well as a poll of 2,000 Republican Hispanic voters and an online survey taken by more than 36,000 people.

With the party at an apparent crossroads, it urged action. The Republican Party, it said, had become "out of touch" and filled with "stuffy old men." It was "talking to itself" rather than reaching out to new constituencies. The perception was, simply, that it did not "care about people."

One election cycle later, the Democratic nominee holds a 20-point advantage among women voters. A recent electoral projection predicted Trump would receive 15% of the Latino vote, by far the lowest for a major-party nominee in recorded history. There are countless other groups of people, like Muslims, who must see a party that has talked about change, about opening up, and has only closed its doors to them — in this case, they literally proposed to do so.

Yep. Screenshot/Twitter

The party is at an unthinkable reckoning point.

Every single Republican candidate for a generation will (rightly) be asked about his or her endorsement of Trump in 2016. Take Sen. Ted Cruz, who, with impeccable timing, resisted endorsing for months only to buy high in September — as Trump creeped up on Clinton in the polls — only to put himself in the awkward pretzel position of sticking by the party's nominee after his biggest scandal.

House Speaker Paul Ryan, meanwhile, disinvited Trump to what had been a planned joint event that also included Wisconsin Gov. Scott Walker, Sen. Ron Johnson, and RNC Chair Reince Priebus. But he, too, has not withdrawn his endorsement.

Ryan, who had also resisted endorsing for months before relenting, is now put in an awkward position: Trump is too toxic to come to Wisconsin, but should be chosen by the American people for the most important job in the world.

"Trump's presidential run is now another one of his lengthy list of bankrupted endeavors where others not only are left to pick up the pieces, but to suffer for Trump's sins," said veteran Republican strategist Evan Siegfried, a prominent Trump critic throughout the race.

Sen. John McCain, the 2008 Republican nominee, withdrew his endorsement of Trump on Saturday, listing a litany of other controversies — a feud with a Gold Star family, his attack on a federal judge because of his heritage, and, most aptly, his assertion that McCain wasn't a "war hero" because he was "captured."

McCain added a fun, fantastical wish in his statement: "He alone bears the burden of his conduct and alone should suffer the consequences."

It's not going to work like that. In fact, it prompts a striking realization: It took an 11-year-old video from the set of a soap opera for so much of the party to finally realize it had had enough.