All the anti-Trump Republicans have

The Ted Cruz-John Kasich alliance failed on Tuesday night as Donald Trump rolled up huge victories in five Northeastern states. The two anti-Trump candidates have only one real option left: to double down on the troubled strategy.

With Kasich out of the way in Indiana next week, Cruz faces a must-win showdown against Trump. If the billionaire takes that state, it may be close to impossible to stop him from winning the Republican presidential nomination. If Cruz prevails, however, his camp and Kasich's already are discussing a plan for dividing up the final huge primaries on June 7.

Trump's pathway to the 1,237 delegates necessary to capture the nomination became easier with big victories on Tuesday. He won more than 100 delegates, putting him less than 300 shy of the magic number.

On the Democratic side, Hillary Clinton continued her seemingly inevitable march to the nomination, winning four of five contests: Pennsylvania, Maryland, Delaware and Connecticut. But Sen. Bernie Sanders, her only rival, won Rhode Island and insists that he will keep competing at least through the final June primaries.

In Indiana, the focus will be on the contest between Trump and Cruz.

Fifty-seven delegates are at stake, about half of them awarded winner-take-all on the basis of the statewide vote. The remainder are awarded winner-take-all in each of the nine congressional districts. Kasich has agreed not to formally compete in the Hoosier state and Cruz, in turn, will stay out of New Mexico and Oregon primaries, which occur later.

Trump dominates the mathematics of the delegate chase and the momentum, too. He is leading in Indiana polls.

His march to the nomination would be slowed if Cruz beat him in that state. Even then, however, Trump would have a big advantage.

In response, the Cruz and Kasich campaigns already are discussing the possibility of extending their pact to the June 7 primaries, when 303 delegates are at stake, including 172 in California.

But such a deal is contingent on how well Indiana works out. The uneasy cooperation, forged at Republican National Committee meetings last week, is already fraying -- Kasich seems uncomfortable -- and has caused some backlash.

A possible arrangement for June 7 might look something like this: Cruz would focus on California and most of the congressional districts; Kasich might limit his presence to 10 or 12 districts, chiefly in northern California.

But the Ohio governor could try to take on Trump in New Jersey, a winner-take-all state. Trump is backed by Governor Chris Christie and has proven unbeatable in other Northeastern states.

Yet Christie is unpopular in his home state and Kasich has a more impressive record as a governor. The case for Kasich might be strengthened by Trump's poor poll ratings in general election match-ups, nationally and in key states. For example, though he won the Pennsylvania primary handily, general election match-ups show Clinton running well ahead of him in the the state.

That's hardly comforting for anti-Trump Republicans, who face a steep uphill slog, but it's all they have.

Previously:
• 04/26/15: Dems' divisions will need healing, too
• 04/21/15: Candidates, please stop whining
• 04/19/15: 2016's Other Big Question Mark
• 04/14/15: Rivals should be in cahoots to stump Trump
• 03/07/15: Hillary's hubris still could trip her
• 02/24/15: Free trade is bipartisan target in 2016 election
• 02/19/15: On Planet Clinton, where everyone's a critic
• 02/09/15: Questions for Bernie Sanders' establishment guy
• 02/03/15: From steadfast Iowa to contrarian New Hampshire
• 02/01/15: Bush's journey from front-runner to straggler
• 01/27/15: Another election, more phony promises on taxes
• 01/19/15: How Cruz supporters differ from Trump fans
• 12/23/15: Why Trump and Cruz aren't Forbes or Cain
• 12/21/15: Speaker Ryan sails through the easy part
• 11/25/15: As the GOP candidates emerge Hillary's weaknesses will be revealed
• 11/05/15: OK, candidates: Ask the questions yourselves. Seriously
• 10/28/15: Imagine an endgame of Cruz vs. Rubio
• 10/26/15:Ted Cruz has a Ben Carson problem in Iowa
• 10/20/15: Will Paul Ryan follow James Polk's playbook?
• 10/20/15: If only Trey Gowdy could meet with Sam Ervin
• 10/13/15: Voters don't like revisiting the trials and tribulations of Clintonland --- but that doesn't mean Hillary can't win
• 09/23/15: Why Jimmy Carter couldn't win the South today
• 09/17/15: Gov. John Kasich's standout record in Ohio
• 09/03/15: Republicans chart 4 paths to stopping Trump
• 08/31/15: Here's how Biden-Warren sort of makes sense
• 08/28/15:Trump upends New Hampshire's substantive tradition
• 08/26/15:Jeb Bush is hugging the wrong president George
• 08/24/15: Underestimating Ted Cruz? That's a mistake
• 08/19/15: US holds steady in a world of economic trouble
• 08/12/15: Who will capture Iowa conservatives after Trump?
• 08/10/15: Debate fireworks that won’t make much impact
• 07/29/15: A plea for conservatives to speak from the heart
• 07/09/15: Ex-Im Bank's undeserved rap for crony capitalism
• 06/24/15: All presidential candidates should be in debates
• 06/03/15: Foreign policy traps await Republicans and Hillary
• 06/01/15: It's small stuff that wrecks presidential runs
• 02/04/15: Can Walker be president without a college degree?

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Albert R. Hunt is a Bloomberg View columnist. He was formerly the executive editor of Bloomberg News, directing coverage of the Washington bureau. Hunt hosts the weekly television show "Political Capital with Al Hunt." In his four decades at the Wall Street Journal, he was a reporter, bureau chief and executive Washington editor, and wrote the weekly column "Politics & People." Hunt also directed the Journal's polls, was president of the Dow Jones Newspaper Fund and a board member of the Ottaway community newspapers. He was a panelist on the CNN programs "The Capital Gang" and "Novak, Hunt & Shields." He is co-author of books on U.S. elections by the American Enterprise Institute and the Brookings Institution.