Donald Trump’s victory in New York stonewalled Ted Cruz’s path to clinching the Republican nomination, making it increasingly difficult to block the GOP front-runner.

The Never Trump forces are pledging to play in Pennsylvania, Maryland, and other states in the Northeast next week, but the prospect for another momentum shift won’t likely come until next month, with races in Indiana and Nebraska, and eventually California in June. The immediate calendar leaves lots of room for Trump to gain steam.

A key part of the problem, strategists say, is that the focus of the effort has been stopping the front-runner instead of promoting an alternative candidate. The movement never truly coalesced around Cruz, and the senator’s endorsements from reluctant Republican colleagues underscored the difficulty his campaign has in engendering excitement for him. Meanwhile, John Kasich now feels emboldened by the notion that Cruz can no longer win the nomination outright. But he and Cruz will be fighting over similar turf in a way that might benefit Trump.

“There’s been this ‘We’ve got to stop Trump,’ but not an equal amount of enthusiasm for ‘Let’s get behind Cruz to do that,’” says John Brabender, a GOP strategist and former adviser to Rick Santorum’s campaign.

“What’s happening is there’s already a transition to more of an inevitability with Donald Trump -- more than there is an excitement to stop him,” he says. “And in that sort of environment, that phenomenon is keeping the anti-Trump crowd from growing in size and volume.”

Ahead of coming primaries, the Never Trump group has endorsed Cruz in Indiana and Pennsylvania and Kasich in Maryland, Connecticut and Delaware. "Donald Trump won’t be stopped in one fell swoop. It will take picking up delegates and districts one at a time all the way through the final contests on June 7," wrote GOP strategist Rory Cooper on behalf of the group.

While Trump’s New York victory was expected, he outperformed most forecasts and won nearly all of the state's 95 delegates. Now he is the only candidate left in the race with a chance at claiming the GOP nod before the convention. The results altered Cruz’s strategy, which is now focused solely on preventing Trump from securing the majority of delegates. And that new goal, strategists say, could drive up both candidates’ negative ratings and make it difficult for the party to unite.

Cruz argues that no candidate will reach 1,237 delegates and that he will overcome Trump at a contested convention. “He knows he can’t earn a majority,” Cruz told reporters at the Republican National Committee spring meeting in Florida. “Donald is a niche candidate. He can’t expand that, and to win you’ve got to have a broad tent, you’ve got to bring in voters other than the hard base.”

Cruz is also trying to court Republicans by arguing that Trump would lose party seats down the ballot. The Texas senator met with party officials on Wednesday.

For his part, the front-runner is behaving like the eventual nominee. "We don't have much of a race anymore,” a triumphant Trump said Tuesday night from his golden Fifth Avenue office building.

On Wednesday, the campaign circulated a memo to surrogates claiming Trump is on track to secure 1,400 delegates before the convention. That goal is most likely a pipe dream, as most estimates figure the delegate race to remain close. But the campaign is trying to convey an aura of inevitability. Trump continues to rail against a “rigged process” in a way that not only rallies supporters but could also appeal to delegates in the final stretch.

At the same time, however, he is making the moves of a more traditional campaign. Before campaigning Wednesday in Indiana, a state where Cruz hopes to turn the tide, Trump met with Gov. Mike Pence. He also gave him a shout-out at his rally, telling Hoosiers that the governor “is really fighting hard for you.” It was a notable departure from his behavior in Wisconsin, where he criticized and poked fun at Gov. Scott Walker.

This all comes amid significant shakeups within the Trump campaign to prepare for the nominating fight ahead. Additionally, Trump recently has tried to steer clear of controversy, focusing on his campaign rather than off-the-cuff remarks. Critics say the moves have come a little too late, and that Trump is bound to fumble soon. “The Trump self-sabotage will come back,” says Sam Nunberg, a former Trump adviser who now supports Cruz.

Trump foes argue the focus of the nominating contest has little to do with states won and everything to do with delegates earned. Trump figures to win Pennsylvania, Maryland, Connecticut, Rhode Island, and Delaware on Tuesday, but Cruz and Kasich are eyeing certain areas within those states to make gains. With the exception of Delaware, which awards all of its 16 delegates to the winner, the rest allocate proportionally.

“All we need to do is prevent Trump from getting to 1,237, and we’re looking at places to hold him below certain thresholds,” Katie Packer, a Republican strategist who heads up Our Principles PAC, told MSNBC, noting the group was in the process of ad buys for the coming contests.

Pennsylvania could provide an opportunity for Trump rivals. The winner collects 17 delegates, and the remaining 54 are unbound and elected directly on the ballot. The Cruz campaign has been organizing to secure those free agents.

The RealClearPolitics polling average shows Cruz and Kasich essentially tied in Pennsylvania for second place. Kasich, who picked off a few delegates in Manhattan on Tuesday, is now training his fire on Cruz while also blaming his struggles on the Never Trump effort, which ceded New York to Trump.

“Ted Cruz’s brand of politics simply won’t play with most voters in Connecticut, Rhode Island, Delaware, Pennsylvania and Maryland,” wrote Kasich chief strategist John Weaver in a campaign memo. “Donald Trump will not be the nominee – if the Never Trump forces get serious. They weren’t serious in New York and allowed Trump to get over 50 percent in numerous districts where he could have been stopped. Continued lack of engagement by Never Trumpers could allow the Trump campaign to get back on track.”

Kasich, however, has shown little ability to thwart Trump. Before Tuesday, he hadn’t earned a single delegate since winning his home state of Ohio in March. He still lags behind Marco Rubio in the delegate count. And his campaign has failed to organize and convert delegates at state conventions and other party gatherings.

Kasich’s lack of operation has compelled anti-Trump Republicans to back Cruz, who has shown organizational prowess. But Trump has turned that asset into a liability, complicating the road ahead.

“Donald doesn't like losing, he doesn't handle it well, and he lashes out at the voters,” Cruz said, referring to Trump’s recent delegate losses at conventions. Cruz argued that more voters showed up in Texas, which Cruz won, than in New York, but that he received fewer delegates than Trump. That’s the way the system works, he said.

But Trump has shined a light on the inner workings of the process, which many argue has made Cruz look like a scheming politician – only because he capitalized on the rules. “It’s a system that’s rigged,” Trump said.

Trump’s fight against the rules of the game could resonate with voters, and has put Cruz and party leaders in the difficult position of having to explain why winning states doesn’t necessarily translate into winning the nomination.

“Trump is a master of the narrative,” says conservative activist and Tea Party co-founder Mark Meckler, who believes the contest will head to a contested convention. “When you're in a national political environment like this, the branding expert is going to win the public fight.”

Meckler says Trump “is doing what he always tries to do to bend the rules so that he profits and everyone else suffers,” but the Cruz campaign has been too academic and has failed to provide a counter narrative.

Cruz also faces a difficult couple of weeks in which Trump will continue to try and build momentum for his nomination. While the senator and anti-Trump forces believe they can keep Trump down in May primaries and in California in June, that’s a long way off. “As Trump starts winning some of these eastern states, you’re going to start seeing a little transition where people say, ‘We gotta figure out how to work with him,’” Brabender says.