Opinion writer
Republican front-runner Donald Trump spoke in Palm Beach, Fla., after primary voters took to the polls in five states: Florida, Illinois, Ohio, Missouri and North Carolina. (Reuters)

THE MORNING PLUM:

Donald Trump romped to victory last night in Florida (effortlessly swatting Marco Rubio out of the race), North Carolina, and Illinois, and the resulting delegate count now means that Trump has a very plausible route to winning an outright majority of the delegates, securing the nomination. However, this is far from assured, and Trump’s latest vault forward has only intensified conversations among Republicans about how to stop him at a contested convention.

But no sooner had this chatter started, then Trump dropped another bomb, by suggesting this morning on CNN that if he finishes with the most delegates, and the nomination goes to someone else, that violence could result:

Trump said Wednesday that a contested GOP convention could be a disaster if he goes to Cleveland a few delegates shy of 1,237 — and doesn’t leave as the party’s nominee.

“I think you’d have riots,” Trump said on CNN.

Noting that he’s “representing many millions of people,” he told Chris Cuomo: “If you disenfranchise those people, and you say, ‘I’m sorry, you’re 100 votes short’…I think you’d have problems like you’ve never seen before. I think bad things would happen.”

It’s hard to say whether this is intended as a threat or a prediction. But the unsettling fact of the matter is that there is no particular reason to rule out the former — that it was indeed intended as a tacit threat, as least of a certain kind. Trump has been playing a clever little game where he hints at the possibility of violence while stopping short of explicitly threatening it — yet he also doesn’t denounce such an outcome as unacceptable, so his hints effectively function as a threat. And as Philip Klein detailed the other day, this could well emerge as an aspect of his convention strategy:

Political commentators now routinely talk about the riots that would break out in Cleveland if Trump were denied the nomination, about how his supporters have guns and all hell could break loose, that they would burn everything to the ground. It works to Trump’s advantage to not try too hard to dispel these notions. He wants Republican delegates who control his political fate to have it in the back of their minds…

Now Trump has made this explicit. Three more points about this. First, it comes right after Mitch McConnell made a very public show of the fact that he privately told Trump that it might be a good idea to “condemn” and “discourage” the idea of violence at his rallies. Trump basically just gave McConnell — and other GOP leaders who surely feel the same way — a big, fat middle finger.

Second, whether or not Trump intended to threaten violence, his latest comments are very significant in another way. Trump explicitly said that if he goes into the convention just shy of a majority of delegates, it would be “disenfranchising” to his voters if the delegates award the nomination to someone else in later balloting. As I’ve reported, some Republicans already worry that if more than one alternative to Trump stays in, it could work against the plot to stop Trump. It could mean the runner-up finishes farther behind Trump in delegates — which end up getting divided between Ted Cruz and John Kasich — thus making it harder to justify giving the nomination to someone else. Trump is essentially saying that if this were to happen, then — violence or not — he will do everything in his power to cast a contested convention as illegitimate, discouraging his supporters not to back the nominee and otherwise doing as much damage to the GOP as he possibly can.

And third, threats like like this could only make it harder for Senate Republicans to continue to refuse to act on President Obama’s Supreme Court nominee. Their implicit position is that President Trump should get to pick that nominee instead, if he wins the general election, a stance that will grow increasingly untenable as Trump looks more and more likely to win the nomination, and simultaneously looks more and more crazy and reckless. But that brings us to our next item.

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* OBAMA TO ANNOUNCE HIS SUPREME COURT NOMINEE: Reuters reports:

Obama will announce his nominee to the U.S. Supreme Court at 11 am E.T. on Wednesday, a source familiar with the selection process told Reuters….Obama is likely to announce either Judge Sri Srinivasan or Merrick Garland as his choice, the source told Reuters.

As I’ve argued, the combination of Trump tightening his grip on the nomination and Obama rolling out an actual nominee could make Senate GOP inaction harder to sustain. Update: It’s reportedly Garland.

* TRUMP TIGHTENS GRIP ON NOMINATION: NBC News’s First Read crew crunches the numbers and concludes that Trump finished last night with 656 of the 1,237 that he needs to win the nomination outright, to 408 to runner-up Ted Cruz. The path ahead:

Trump needs to win 55% of remaining delegates (including 60 left from last night)…Cruz needs to win 79% of remaining delegates…Kasich needs to win 104% of the remaining delegates.

So it’s still very possible to force a contested convention, but Kasich and Cruz both staying in could split the non-Trump vote in the remaining states, which could make that less likely.

* CLINTON’S PATH TO NOMINATION CLOSE TO ASSURED: Clinton racked up victories in Florida, Ohio, North Carolina, and Illinois, ending the night with a pledged delegate lead of around 300. Nate Cohn explains how daunting the road has become for Bernie Sanders:

About half of all of the pledged delegates to the Democratic convention have been awarded. To prevail, Mr. Sanders will need to win from here till the finish by a 15-point margin….The next month includes numerous favorable contests: Utah, Washington, Idaho, Alaska, Wyoming and Wisconsin. But Mr. Sanders is unlikely to win by such huge margins in the delegate-rich, affluent and diverse states along the coasts like California, New York, New Jersey and Maryland. There he needs big wins to counter Mrs. Clinton’s commanding delegate lead.

In other words, it isn’t enough for Sanders to rack up a string of victories from here on out; they would have to be very big victories that average out to a double digit advantage. That seems unlikely.

* BUT SANDERS TEAM STILL PLOTS LONG-SHOT VICTORY: Despite falling way behind in the pledged delegate and superdelegate count, Politico reports that the Sanders camp still sees a way to the nomination, one that turns on using momentum in coming states to flip superdelegates:

Sanders’ campaign thinks the next few weeks of the campaign calendar favor him and is preparing plans to make the uphill case to the super-delegates — the 718 activists and elected officials who can vote however they please — that his late-breaking momentum would make him a stronger nominee that they should support over Clinton….Sanders campaign aides say they’ll be able to keep Clinton from reaching the 2,383 delegate magic number she’d need to clinch the nomination at the convention and, by being close enough, convince the superdelegates to switch.

Even if Sanders did manage to win a lot more contests down the road, it seems highly unlikely that a lot of superdelegates would switch to Sanders on the theory that he is more electable than Clinton is, but one supposes anything is possible.

* SANDERS PLEDGES TO GO ALL THE WAY TO CONVENTION: Just in from Senator Sanders this morning:

“I congratulate Secretary Clinton on her victories on Tuesday. I also want to thank the millions of voters across the nation who supported our campaign and elected delegates who will take us all the way to the Democratic National Convention in Philadelphia. With more than half the delegates yet to be chosen and a calendar that favors us in the weeks and months to come, we remain confident that our campaign is on a path to win the nomination.”

I don’t know if Sanders is actually confident of that or not. But he has the money to keep going, and he has every incentive to do so, since he can continue to build his movement and in the process, maximize his leverage later.

* GOP BRACES FOR BRUTAL CONVENTION BATTLE: The Washington Examiner reports that the question of whether a contested convention can nominate someone other than Trump turns on whether the rules committee rewrites convention rules to make it possible:

Without a presumptive nominee to oversee the process, delegates on the panel would be the subject of intense lobbying by the campaigns to craft regulations governing the convention that might undermine their competitors in the floor vote….The rules committee is comprised of convention delegates, who are themselves elected….The Cruz, Kasich and Trump campaigns have formed teams to work on electing delegates that will support their candidate on the convention floor.

So Trump might successfully get some of his people on to the committee. You can be certain that this is going to be an epic, rolling, carnivalesque mess.

* WILL PAUL RYAN SEEK GOP NOMINATION? In an interview with John Harwood, Paul Ryan says:

“People say, ‘What about the contested convention?’ I say, well, there are a lot of people running for president. We’ll see. Who knows.”

Of course, Ryan has a pretty good day job right now that he might not want to give up. Indeed, his spokesperson, AshLee Strong, quickly clarified that Ryan also said in that interview: “I’m happy where I am, so, No.” However, he said something similar about running for Speaker…