There are warning signs for Trump inside victory numbers | McClatchy Washington Bureau

Donald Trump’s victories Tuesday in Michigan and Mississippi inched him crucial steps closer to the Republican nomination, as he increased his lead in the race for the 1,237 delegates needed to nominate.

But danger signs emerged as he struggled to expand his support beyond his long-devoted following. A troubling pattern in Michigan and Mississippi built on earlier results and could pose a growing threat in days ahead: Late-deciding voters are breaking for rivals.

Trump’s challenge as he heads into a mega-showdown next Tuesday in Florida, Illinois, Missouri, North Carolina and Ohio is that he’s not growing his base support. As long as he faces a multi-candidate field, he can still win. But if that field shrinks, late-breaking voters unwilling to back Trump might coalesce behind one candidate and slow, if not threaten, his march to the nomination.

His momentum was shaken last week by his uncertain debate performance and by 2012 Republican nominee Mitt Romney’s blast questioning Trump’s credibility and charter.

The numbers illustrate Trump’s still-wobbly front-runner status. He has the backing of 34 percent of Republicans in a March 3-6 Washington Post/ABC poll, down from 37 percent in January.

Trump on Tuesday insisted he had weathered a barrage of criticism throughout the week and emerged strong. “So many horrible, horrible things said about me in one week,” he told supporters in Florida.

Gov. John Kasich of Ohio saw a strong finish in Michigan as a sign that he can win late-deciding voters and gain support heading into Ohio next week and other states.

“Governor Kasich surged to an unexpectedly strong finish,” campaign strategist John Weaver said in a memo to supporters. “Governor Kasich won late deciders in Michigan.”

Weaver cited his campaign’s consistent strategy. As the GOP field shrinks, he said, Kasich’s “positive message and proven record will begin to break through.” After March 15, he said, more than 1,000 delegates will be available, many in what appear to be Kasich-friendly states such as New York, Pennsylvania and New Jersey.

Since voting began five weeks ago with the Iowa caucus, exit polls in state after state have shown that Trump’s supporters decided long before their state’s primaries or caucuses to back him. But among those who decide a week or less before the election, Trump nearly always runs behind his rivals.

That trend surfaced again Tuesday. In Michigan, Trump won half the voters who made up their minds before the last week. But since then, Kasich surged, taking 42 percent of the late deciders. Sen. Ted Cruz of Texas was second, with one-fourth of that vote, followed by Trump with 20 percent.

In Mississippi, Trump won 55 percent of those who’d decided on candidates earlier than last week. Among those who’d decided in those final days, Cruz topped Trump, 39 to 28 percent.

Trump remains strong among the legions of voters highly dissatisfied with government and fuming at power brokers they see presiding over a sluggish economy, an out-of-control immigration system and a lax national security system.

Those are deeply held anxieties, and Trump articulates them as few top politicians have in recent years, said Steve Mitchell, chairman of a Michigan-based research and communications firm.

At the same time, he said, people are paying unusually close attention to the Republican race. “If something happens nationally, people in Michigan know it,” Mitchell said.

So if Trump stumbles, as he did in last Thursday’s debate with a veiled reference to his genitals, it may be a stop sign for wavering voters thinking of voting for him. “It was a bit too much for even some of his die-hards,” said Patrick Murray, director of the Monmouth University Polling Institute, which conducts Michigan surveys.

The more Trump is argumentative, the less he attracts last-minute deciders.

In Massachusetts’ primary March 1, he won 60 percent of the early deciders – but only half that many among late deciders.

In Tennessee, he was ahead of Cruz by 47 to 21 percent among the early deciders. But those making up their minds in the final week broke for Cruz and Sen. Marco Rubio, R-Fla., ahead of Trump.

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The tendency continued: Trump was up by 10 over Rubio in Virginia among early deciders, down 20 to Rubio among latecomers. Trump was up 25 over Cruz among early South Carolina deciders, then a distant third behind Rubio and Cruz among those deciding in the last few days.

Trump continues to win, though, because none of the challengers can sustain any momentum. Even on Tuesday, Kasich was the beneficiary of the late deciders in Michigan but barely was visible in the Mississippi results.

Their showings, though, suggest that if this trend continues, no one will enter the Republican convention in Cleveland with enough delegates to win the nomination. And that could mean the first multi-ballot convention since Democrats nominated Adlai Stevenson on the third ballot in 1952.

Trump now faces crucial tests on several fronts next week that will shape the future of the race. Kasich’s finish in Michigan suggests he’s a threat to Trump certainly in winner-take-all Ohio, but also Illinois.

Rubio, who faltered badly Tuesday, is pouring resources and spending most of his time in his home state, where 99 delegates are at stake. "It has to happen here, and it has to happen now," the senator told a Sarasota rally. Cruz retains a sizable following among die-hard conservatives, an asset in next week’s North Carolina primary.