On the morning after, one thing is clear: the Republican Party is at a crossroads.
Many party leaders and establishment Republicans see two paths ahead. One is to accept what appears to be the increasingly likely outcome in the 2016 race — that Trump will soon clinch the GOP nomination — and offer the New York businessman their blessing. The second is a path of a historic rebellion: rejecting the GOP front-runner and the values and principles he stands for, and pledging to oppose Trump — even if he emerges as the party's nominee.
Former Minnesota Gov. Tim Pawlenty, who ran for president in 2012, described this moment as an "inflection point" in the 2016 race and for the Republican Party.
"The party is fractured, which isn't unusual for political parties and they almost always come back together. But this could test the outer limits of that tradition," Pawlenty, who endorsed Marco Rubio, told CNN. "If the Republican Party were an airplane and you're looking out the window, you'd see some pieces of the surface flying off. And you'd be wondering whether the engine or a wing is next."
With Trump adding delegates to his quickly growing stash Tuesday, political veterans suspect the GOP presidential race could reach a moment of unambiguous clarity in the next two weeks. That point could come on March 15 when Florida and Ohio vote. If Rubio, the Florida senator, and John Kasich, the Ohio governor, lose their home states, their campaigns would be doomed.
Former Senate Majority Leader Trent Lott put it this way: By March 15, Republicans will know whether it is time to "throw up our hands in despair and panic."
"We've now backed ourselves into a corner here -- and it's not very pretty," said Lott, who is supporting Kasich. Super Tuesday, Lott added, "is not the final blow, but we will know in the next two weeks whether this is a done deal or not."
Flurry of discussions
In recent days, there has been a flurry of discussions among top Republican strategists and insiders about how to distance the party from Trump. His heated rhetoric about minority groups and immigrants is deeply troubling to party leaders who have spent years trying to make inroads with Latino and other minority constituencies. Also of grave concern are the down-ballot candidates who would face tough elections in November with Trump at the top of the ticket.
Disaffected Republicans are discussing everything from skipping the Republican National Convention in July to running a conservative candidate as an independent or third-party candidate -- with the ultimate goal of denying Trump the presidency. One of the names frequently mentioned in this hypothetical is Mitt Romney, the 2012 GOP presidential nominee, even though he has shown no desire to run another campaign but has shown a zest for attacking Trump.
Trump's dominance on Super Tuesday caps the GOP front-runner's remarkable rise as a first-time presidential candidate. His initial surge in the polls months ago was widely dismissed as a short-lived phenomenon. His divisive and inflammatory rhetoric on everything from immigration to women drew fierce scorn from fellow Republicans and Democrats alike.
But Trump's candidacy has proven shockingly durable, and his supporters exceptionally loyal.
His dominant night comes just days after another development shocked the party to its core: New Jersey Gov. Chris Christie's bombshell endorsement of the billionaire last week. Christie ended his own presidential bid last month, and the unexpected decision from the former chairman of the Republican Governor's Association to back Trump — the ultimate anti-establishment candidate — added a critical sense of credibility to the businessman's candidacy.
Christie's endorsement was quickly followed by the backing of Maine Gov. Paul LePage and Alabama Sen. Jeff Sessions.
Former House Speaker and presidential candidate Newt Gingrich, who has no plans to endorse a candidate in the GOP primary, said he was "shocked" by Christie's decision, and that the slew of new endorsements have irreversibly changed perceptions of Trump's candidacy.
'Very unique coalition'
"Trump is putting together a very unique coalition that's rattled a lot of people who have made a living out of trying to win within a Republican structure which is now increasingly obsolete," Gingrich said. "A lot of people smugly said when we get down to reality, he is not going to be the nominee because in the end people aren't going to vote for him. Well, guess what — he's almost certainly going to be the nominee."
As Trump has started to pick up endorsements from serious conservative leaders including a handful of members of Congress, a fierce anti-Trump movement has started to pick up steam.
Republican operatives, party leaders and conservative thinkers are increasingly warning that Trump is not a true conservative, and that his penchant for offensive language proves that he's an entertainer who should have no role shaping the future of the Republican Party. These rumblings turned into a movement on social media marked with the hashtag "#NeverTrump" -- a vow to never back Trump, even if he becomes the nominee.
But these last-minute strategy sessions underscore the fundamental lack of a coordinated effort in the party to derail Trump's campaign. Many are simply resigned to accepting that this far along in the election, and considering the delegate math, no amount of money or anti-Trump messaging can slow the front-runner's momentum.
Over the weekend, Trump only fueled the anger directed at his campaign when he failed to denounce white supremacist groups.
"I don't know anything about David Duke, OK?" Trump told CNN's Jake Tapper when asked whether he would disavow the Ku Klux Klan grand wizard, who is supporting Trump's campaign. Pressed several times, Trump insisted he didn't know anything about white supremacists.
The interview unleashed fierce backlash.
On Sunday evening, GOP Nebraska Sen. Ben Sasse
became the first member of Congress to join the #NeverTrump movement. If Trump wins the GOP nomination, Sasse said he would look for a third-party alternative.
"I'm not going to vote for Hillary Clinton, and given what we know about Donald Trump, I can't vote for that guy either," the first-term senator said.
House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell took Trump to task on Monday
, saying Republicans must unequivocally reject racism.
But the anti-Trump campaign is also angering some party elders. They say rejecting the GOP nominee is tantamount to handing the election to the eventual Democratic nominee, widely expected to be Hillary Clinton, who had a strong night on Super Tuesday.
Former Wyoming Sen. Alan Simpson, who supported Jeb Bush's failed White House bid, told CNN that these rebelling Republicans may as well be casting their votes for Clinton. He also expressed deep frustration at the party for failing to rally around a single alternative to Trump, like Bush or Kasich, early enough in the election.
"Just go ahead and support Hillary and forget it!" said Simpson. "They may not like Trump -- they didn't like Bush. What the hell was wrong with Bush? What the hell is wrong with Kasich?"
Gingrich, who pledged to back the party's eventual nominee, predicted that many of his fellow Republicans who now say they could never support Trump will eventually change their minds.
"The absence of voting for the Republican nominee is functionally a vote for Hillary," Gingrich said. "It's a crossroads for the Republican Party and it's a crossroads for America."