The Ides of March has long loomed large on the political calendar, but with all due respect to Julius Caesar, it's quite the killer date this year. Not only are at least two of the remaining Republican presidential candidates on the verge of departure from the race (at the hands of their home states, no less) but front-runners Donald Trump and Hillary Clinton are poised to make potentially decisive gains in the all-important delegate tally.

Much of the focus will be on Mr. Trump, of course. From the sometimes-violent clashes at his rallies between supporters and protesters to the last-gasp Stop Trump movement that would have the GOP nominate anybody-but-The-Donald, the billionaire developer remains at the center of the political storm — which always seems to be his goal. But if anyone thought that the weekend's controversies and hate-filled rhetoric — by, on behalf of and against Mr. Trump — would stall his momentum, that person obviously hasn't been watching this particular election and the candidate's nature.

Mr. Trump can't win the nomination outright, even if he wins Florida, Ohio, Illinois, Missouri and North Carolina, but because most of those states award delegates on a winner-take-all basis, he could easily come away with a decisive lead. A predicted Trump victory in Florida is likely to mean the end of the road for the presidential ambitions of Sen. Marco Rubio. And while Gov. John Kasich may yet eke out a win in his native Ohio and thus stick around (the most recent polls show him neck-and-neck with Mr. Trump), it could be offset by Trump victories in Illinois and Missouri.

Should Mr. Trump win all those states, his delegate count would essentially put him on a glide path to victory. Lose Ohio, and the nomination is not necessarily in the bag, but momentum would still be on the real estate developer's side. In the unlikely event that Mr. Trump were to lose both Ohio and Florida, that would be another story — the possibility of a brokered convention would suddenly seem possible again, with Sen. Ted Cruz looking like the front-runner's most formidable opponent.

Meanwhile, Hillary Clinton appears to be in an even stronger position in her battle to secure the Democratic nomination. Last week's Michigan victory by Sen. Bernie Sanders demonstrated his appeal in the Rust Belt, where concerns over trade agreements and the loss of manufacturing jobs have proved a Clinton liability. But even if states like Ohio, Missouri and Illinois “feel the Bern,” what chance does that give the Vermonter, who already trails in the delegate count by a greater than 2-to-1 margin against Ms. Clinton, who appears to have the South (Florida and North Carolina included) locked up?

That Ms. Clinton has already pivoted to heap criticism on Mr. Trump and his handling of violence at his rallies signals the candidate's growing confidence about where she stands. She could easily take Florida, today's biggest single prize, in a landslide, and while polls suggest tighter races in the other states, she'll still be running ahead. A sweep, and the race is essentially over.

Much has been written in recent days about how Republicans deserve the Frankenstein's monster they've created in Mr. Trump, with his anti-immigrant and anti-Muslim rhetoric and dumbed-down policy pronouncements. His rallies have produced a level of passion — and perhaps yielded an upswing in primary voter turnout — unmatched on the Democratic side. Yet for all that spectacle, Mr. Trump has only captured a plurality of votes, not a majority, and only in one political party. Anti-Trump sentiment remains a powerful force in the electorate, Republicans included, an Achilles' heel that may yet spell the candidate's doom if GOP moderates abandon him and Democrats are highly motivated to oppose him in November.

As Cassius once observed in questioning his leader's unchecked ego and fame, “Upon what meat doth this our Caesar feed that he is grown so great?” The Ides of March may prove a triumph for the man who leads the Republican field through a toxic concoction of TV celebrity, working-class voter anger, a too-crowded field of candidates and fortuitous timing. Like all Shakespearean tragedies, it is both riveting to watch and certain to ultimately prove dispiriting to its audience.