The presidential campaigns of Texas Sen. Ted Cruz and Ohio Gov. John Kasich said Sunday they are collaborating to deprive front-runner Donald Trump the delegates needed to win the Republican nomination.

"Having Donald Trump at the top of the ticket in November would be a sure disaster for Republicans," Cruz's campaign manager, Jeff Roe, said in a statement. "To ensure that we nominate a Republican who can unify the Republican Party and win in November, our campaign will focus its time and resources in Indiana and in turn clear the path for Gov. Kasich to compete in Oregon and New Mexico, and we would hope that allies of both campaigns would follow our lead."

Cruz Campaign Releases Statement on Upcoming Primaries: https://t.co/8GcWdXQ4aO — Team Cruz (@TeamTedCruz) April 25, 2016

Trump needs 1,237 delegates to win the Republican nomination. If he falls short, the national Republican gathering in July will evolve into a rare contested convention.

Currently, Trump leads with 845 delegates while Cruz trails with 543 delegates and Kasich holds just 148 delegates while nearly 700 delegates remain up for grabs. Marco Rubio, who suspended his campaign in March, has 171 delegates.

Over 150 delegates will be up for grabs on Tuesday when primaries are held in five states with the biggest prize being Pennsylvania.

Trump has repeatedly denounced the system, saying he should win the nomination even if he falls slightly short of the majority — something officials with the Republican National Committee have ruled out.

I suppose the Cruz/Kasich deal is smart, but I wonder if being so public about it is smart as opposed to coordinating behind the scenes. — Nate Silver (@NateSilver538) April 25, 2016

Both Cruz and Kasich's campaigns view Indiana's winner-take-all contest on May 3 as the critical turning point for thwarting Trump's rise to the nomination.

"Keeping Trump from winning a plurality in Indiana is critical to keeping him under 1,237 bound delegates before Cleveland," Kasich's campaign said Sunday. "We are very comfortable with our delegate position in Indiana already, and given the current dynamics of the primary there, we will shift our campaign's resources west and give the Cruz campaign a clear path in Indiana."

NEWS: Kasich campaign will marshal campaign resources to New Mexico and Oregon, allow Cruz to focus on Indiana. pic.twitter.com/auUIUX961O — Team Kasich (@TeamJohnKasich) April 25, 2016

Late Sunday night, Trump responded via Twitter.

Wow, just announced that Lyin' Ted and Kasich are going to collude in order to keep me from getting the Republican nomination. DESPERATION! — Donald J. Trump (@realDonaldTrump) April 25, 2016

Additional reporting by Mashable.

Have something to add to this story? Share it in the comments.