Don’t be­lieve the con­ven­tion­al wis­dom that the Cruz-Kasich deal is a stra­tegic mis­fire, one that comes too late in the pro­cess to make a dif­fer­ence. It’s a crit­ic­al de­vel­op­ment in a state where there’s an anti-Trump ma­jor­ity that’s di­vided between Cruz and home-state neigh­bor Kasich. The same con­sol­id­at­ing tac­tics al­lowed Cruz to trans­form a close Wis­con­sin race in­to a blo­wout in his fa­vor. Even without a gubernat­ori­al en­dorse­ment (In­di­ana Gov. Mike Pence is un­likely to jump on the #StopTrump train) and a uni­fied talk-ra­dio front against Trump, all it takes for Cruz to be­ne­fit is a nar­row vic­tory. And if past is pro­logue, Trump’s band of sup­port in Mid­west­ern states is con­sist­ently nar­row: He took 39 per­cent of the vote in Illinois, 36 per­cent in Michigan, 36 per­cent in Ohio, and 35 per­cent in Wis­con­sin. He’s now polling at 39 per­cent in In­di­ana, ac­cord­ing to the Real­Clear­Polit­ics av­er­age, be­fore the cav­alry comes in for Cruz.

Anti-Trump groups such as the Club for Growth and Our Prin­ciples PAC are now pour­ing mil­lions in­to In­di­ana to broad­cast a sin­gu­lar stop-Trump, pro-Cruz mes­sage. Un­like New York and the North­east­ern primary states, it’s in­ex­pens­ive to air ads in most of In­di­ana’s me­dia mar­kets. Out­side groups have mostly held their fire since Wis­con­sin. They’re com­ing back with a ven­geance in In­di­ana, with anti-Trump groups out­spend­ing pro-Trump groups by a 4-to-1 ra­tio. If the battle for the nom­in­a­tion was defined by mo­mentum, it’s fair to as­sume Trump could con­sol­id­ate sup­port with his North­east­ern sweep. But this race has been about everything else. (Trump won big on Su­per Tues­day, only to be dealt caucus set­backs days later; he dom­in­ated in pivotal big-state primar­ies on March 15 only to flail in Wis­con­sin.) The re­gion­al dif­fer­ences in Trump’s sup­port have been sig­ni­fic­ant, and it’s more likely that tac­tics will define the In­di­ana primary more than Trump’s re­cent string of home-field vic­tor­ies.

And yes, calls for stra­tegic vot­ing have worked in the primary pro­cess in cru­cial in­stances. In the run-up to the Ohio primary, Marco Ru­bio called on his sup­port­ers in the state to back Kasich. Ru­bio only won a tiny 2.3 per­cent of the GOP vote, a clear sign that most of his sup­port­ers heeded his calls. After Wis­con­sin Gov. Scott Walk­er told anti-Trump Re­pub­lic­ans to back Cruz, not Kasich, the Ohio gov­ernor’s sup­port col­lapsed throughout the state.