Reuters/Carlo Allegri
Donald Trump.
Their goal is to prevent the frontrunner from reaching the needed 1,237 delegates to secure the Republican nomination ahead of the July convention.
The plan has Kasich's campaign essentially conceding Indiana, the next state up to vote, to Cruz. The Texas senator's campaign, meanwhile, will back out of Oregon and New Mexico and let Kasich, the Ohio governor, devote resources to the Western states.
But for Kasich and Cruz, the plan has three major flaws:
1. The math doesn't quite add up
Indiana, a state with 57 delegates on the line, is winner-take-all by congressional district and in the statewide vote. It's a huge state for the candidates looking to stop Trump - him winning the state would put him well on the path to the 1,237 delegates.
But it's not essential to Trump's endgame. Recently, MSNBC's Steve Kornacki projected that Trump could secure the nomination during the first ballot at the convention while winning just nine of the 57 delegates in the Hoosier State.
Nate Silver of FiveThirtyEight wrote that Trump would need 48 delegates in the state to hit the needed 1,237 total, but his equation did not factor in the number of unbound delegates from Pennsylvania that could vote for Trump on the initial ballot.
And in New Mexico and Oregon, two proportional primaries, both Kornacki and Silver projected that Trump wouldn't even need half of the delegates at stake to consider each a success.
2. Not all of Kasich's supporters will vote for Cruz - and vice-versa
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But it's not that simple.
For example, in a recent Fox News poll, 22% of Kasich supporters said Trump was their second choice in the Hoosier State, while 53% said Cruz would get their vote if Kasich was out of the equation.
Overall, 16% of respondents had Kasich as their first choice.
With those numbers factored in, Trump's lead would shrink from an 8 points to a 3 points. He's still leading.
Also, although both campaigns have announced they'd "allow" the other candidate to "focus" on the states in question, the Kasich and Cruz themselves have not yet asked voters to vote for the opposite candidate in Indiana, New Mexico, and Oregon.
Indeed, when asked Monday for whom Indiana voters should cast their ballots, Kasich reportedly said, "They ought to vote for me."
3. It plays into Trump's "rigged" argument
After Cruz and Kasich announced the plan to work together in an effort to block Trump, the Manhattan billionaire released a scathing statement on the pair that falls in line with his weeks-long argument that the GOP's nominating process is "rigged."
"It is sad that two grown politicians have to collude against one person who has only been a politician for ten months in order to try and stop that person from getting the Republican nomination," Trump said in the statement.
The appearance of two candidates joining forces specifically in an effort to block Trump from accumulating delegates seems to play into that argument.
"They are mathematically dead and this act only shows, as puppets of donors and special interests, how truly weak they and their campaigns are," Trump wrote in the statement, later adding "Because of me, everyone now sees that the Republican primary system is totally rigged."
Trump lambasted the delegate-selection process since Cruz began picking up delegates en masse in states such as Colorado and Wyoming, which both held conventions instead of a more traditional primary or caucus. With the agreement between Cruz and Kasich aimed at minimizing the number of delegates Trump can acquire, the storyline is sure to flourish once again.
Trump said in the statement: "This horrible act of desperation, from two campaigns who have totally failed, makes me even more determined, for the good of the Republican Party and our country, to prevail!"