Analysis: Mitt Romney's long, detailed and passionate speech attacking Donald Trump Thursday was one of the most important moments of the 2016 campaign.
It was the clearest, sharpest break by the traditional, establishment wing of the GOP from the candidate who is winning the most votes. Even if Romney does not sway many Republican voters away from Trump, the speech and its favorable reception by some leading Republicans (Arizona Sen. John McCain praised Romney's address immediately after it concluded) creates a permanent fissure in the GOP.
If Trump is the nominee, Romney will be very, very unlikely to speak at the Republican National Convention in Cleveland, as past nominees of major parties usually do. A Trump victory in the nomination process, after Romney blasting him on Thursday, will be a complete repudiation of Romney and McCain, the last two Republican nominees, and the more tempered conservatism they ran on.
And Romney, by arguing Trump is completely unfit for the American presidency, has suggested Republicans should not feel comfortable with casting ballots for him in the general election, even if he is running against Hillary Clinton, who is hated by many conservatives.
If even a small bloc of Republicans heed Romney's advice and opt not to vote for the business mogul in a general election, Trump will have little chance of becoming president unless he is able to forge a new coalition of voters - namely nonvoters and Democrats - that makes up for the loss of some traditional Republicans.
"This is a pretty searing indictment. Trumpites won't care. The sane majority will," said Rick Wilson, a Republican strategist based in Florida who is a strong opponent of the mogul.
Romney's speech was notable in another way: it illustrated the deep and bipartisan opposition to Trump. In January, President Obama spent much of his final State of the Union address warning against the rise of Trump-style politics. Almost two months later, the man who ran against Obama in 2012, Romney, went further, devoting an entire address to Trump's flaws.
Romney suggested the mogul is racist, sexist, stupid, dishonest and mean. And he said Trump would be an embarrassment to Americans on the world stage.
"The President of the United States has long been the leader of the free world. The president and yes, the nominees of the country's great parties help define America to billions of people. All of them bear the responsibility of being an example for our children and grandchildren," Romney said.
He added, "Think of Donald Trump's personal qualities, the bullying, the greed, the showing off, the misogyny, the absurd third grade theatrics."
In the short term, it's not clear how much impact Romney's speech will have politically. He was unwilling to endorse one of Trump's rivals and encourage the party to rally around either Texas Sen. Ted Cruz, Florida Sen. Marco Rubio or Ohio Gov. John Kasich.
Romney instead said Republicans should back any one of that trio, raising the possibility that anti-Trump voters will continue to split their votes.
And it's unlikely the views of the elite, Harvard-educated Romney will sway the non-college-educated cohort that is driving Trump's success.
"The guy [who] wrote off 47 percent of the country is now attacking the guy who is broadening the reach of the party," said conservative talk show host and Trump enthusiast Laura Ingraham in a Twitter message after Romney's speech.
She added, "It's good to see Romney really fighting for something. If only he had cared this much about stopping Obama."
David Brody, the political correspondent for the Christian Broadcasting Network and one of the first reporters to describe Trump's deep appeal to evangelical Christians, wrote:
But even if it has no electoral impact, Romney's speech was momentous. Trump led for months in polls, then won 10 of the first 15 Republican primaries. He has a big lead among Republican delegates, is expanding his base of support among GOP voters and even starting to get the backing of party elites like New Jersey Gov. Chris Christie and Alabama Sen. Jeff Sessions.
In a normal race, a person like Romney would be giving a speech urging other Republicans to fall in line behind the person who has won two thirds of the primaries and is the presumptive nominee.
Instead, Mitt Romney has declared war on Trump and his voters.