First he went after "Little Marco" Rubio. Then he targeted "Lyin' Ted" Cruz.
Now as he faces a key test Tuesday in Ohio, a state that could ease his way to the Republican nomination or raise a significant hurdle, Donald Trump has turned his sights on its governor, presidential rival John Kasich.
He has yet to land on the sort of pithy put-downs he plastered on Florida Sen. Rubio or Texas Sen. Cruz, though "absentee governor" is an oft-repeated criticism of Kasich, who has vacated Ohio for long stretches of his second term.
Instead, Trump has served up a smorgasbord full of scorn: Kasich is a baby. Kasich is weak. Kasich is a loser. Kasich isn't very bright. Kasich helped tank the economy as a Lehman Bros. executive. Kasich voted for lousy trade deals that have punished Ohio's workers.
"Your coal industry is dead. Your steel industry is dead," he told an audience Monday night in Youngstown. "Your governor is totally overrated."
The shift in tone and emphasis, after Trump long ignored Kasich, reflects the reality facing the New York businessman and GOP front-runner on one of the biggest voting days of the nominating season.
Five states will hold primaries Tuesday, including North Carolina, Missouri and Illinois, with 358 delegates at stake. That is more than a quarter of the number needed to claim the GOP nomination.
But the most important balloting will be in winner-take-all Florida and here in Ohio, testing Rubio and Kasich where voters know them best. A loss at home would force both to give up on the race, leaving just Cruz, who has demonstrated limited appeal, as the last candidate facing Trump.
A sweep of the two states and their combined 165 delegates could all but cinch the nomination for the New York business magnate.
Cruz continued to insist he would be the stronger of the two in a general election against Democratic front-runner Hillary Clinton. "If we nominate Donald Trump, Hillary wins," Cruz said at an Illinois stop Monday in heavily Republican DuPage County.
In Florida, Rubio struck a contemplative tone, comparing the tumultuous campaign to a broader shake-up of the country's values.
"We have a culture today where what used to be wrong is now considered right," the senator told a crowd at Palm Beach Atlantic University.
He cited Trump's often outlandish rhetoric — "We never had a presidential candidate that has to be bleeped out" — but conceded he bore some responsibility for the raunchy tone of the campaign, saying he "felt terrible" for his crass swipes at the front-runner over his tan, his hair and, implicitly, his genitals.
"It embarrassed my children," he said. "It embarrassed my wife."
Polls suggest Trump is well ahead in Florida, where he lives part time in a Palm Beach mansion. But in Ohio, Trump's lead in surveys has turned to a slight advantage for Kasich as the contest comes into sharper focus and the news since Friday night has been filled with accounts of violence at a Trump rally in Chicago.
In a sign of his concern, Trump canceled an election-eve rally in Florida and added the event Monday night outside Youngstown, an archetypal Rust Belt city filled with the white working-class voters who have been among his strongest supporters.
"We've got to beat Kasich," he said. "He's not going to be a great president."
Kasich's reaction to the mayhem in Chicago was to blame Trump. The governor accused him of fomenting a "toxic environment" that has poisoned the country's politics and said the images from the near-riot sent an embarrassing message around the world.
"Our enemies are going to take advantage of them," he said at a Sunday campaign stop outside Cleveland. "Our friends are scratching their heads saying, 'What the heck is happening in America?'"
The sharper edge represents a shift for Kasich as well, who had positioned himself throughout the Republican contest as the one candidate who refused to stoop to sniping that others engaged in. "I am not going to take the low road to the highest office in land," he said Monday night, drawing a huge cheer at a hometown rally in Westerville with what remains one of his standard lines.
But the stakes in Ohio are arguably higher for Kasich than Trump. A defeat and subsequent withdrawal from the contest would mark the second time he has run for president and lost and, at age 63, could spell the end of Kasich's national ambitions.
For all of Trump's name-calling, he has substantive differences with Kasich.
As a member of Congress, Kasich voted for the North American Free Trade Agreement, a pact with Canada and Mexico that removed all tariffs and quotas between the U.S. and the two countries. Trump blames NAFTA for decimating wide swaths of the country's manufacturing base.
"Ohio has never ever come back from that," Trump said at an appearance Sunday in West Chester, a Cincinnati suburb.
They differ over Common Core, the recommended federal education standards, which Trump has criticized.
One of the most significant areas of disagreement is over immigration, with Kasich opposing Trump's proposal to round up and deport the estimated 11 million people living in the United States illegally. As president, Kasich said in a debate last week, he would give them an opportunity to stay, though not obtain citizenship.
If America hadn't welcomed immigrants like his mother, Kasich said, "I'd be running for president of Croatia."
Inevitably, the two have taken their fight to Ohio's airwaves, with each pummeling the other in millions of dollars' worth of negative ads.
A political action committee supporting Kasich has aired a spot accusing Trump of attacking "our" Kasich with "baldfaced unhinged lies." The closing screen features a sour image of the reality TV star and the words, "Ohio doesn't trust Trump."
Trump's attack ad accuses Kasich, among other things, of helping "Wall Street predator Lehman Bros. destroy the world economy."
For several years after leaving Congress in 2001, the governor worked for the investment bank, whose collapse helped precipitate the Great Recession. He responded with sarcasm.
"I ran a two-man office in Columbus, Ohio," he told reporters. "And if I bankrupted Lehman Bros. from a two-man office I should have been selected pope, not run for president."
Times staff writers Cathleen Decker in Youngstown, Melanie Mason in Miami and Chris Megerian in Sacramento contributed to this report.
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