Story highlights Primary contests took place Tuesday for Republicans and Democrats in states including Florida, Missouri and Ohio

Tim Stanley: Donald Trump has changed his party for good. Or wrecked it, depending on your point of view

Timothy Stanley, a conservative, is a historian and columnist for Britain's Daily Telegraph. He is the author of "Citizen Hollywood: How the Collaboration Between L.A. and D.C. Revolutionized American Politics." The opinions expressed in this commentary are his.

(CNN) Let's dispel once and for all with this fiction that Marco Rubio will be the 2016 Republican nominee. After a humiliating defeat on Mega Tuesday, he finally bailed out -- closing down his campaign with an emotional speech that begged Republicans not to "surrender" to anger and fear. They almost did: Donald Trump scored big victories across the country and added hugely to his delegate count. But John Kasich's victory in Ohio may have prevented his coronation. And so the baton is passed: we have a new contender for second place.

The exit polls told us a lot of what we've heard before. Trump appeals to the less well educated, the poorer and, often-times, the older voter. Kasich won Ohio by dominating among moderates and the upper-middle-class . It's tempting to dismiss his victory given that it came in his home state -- the political equivalent of getting a Valentine's Day card from your mother. But compared to the rout that Rubio suffered in Florida, it sounded like a ringing endorsement from party moderates desperate to find a new leader. And it came at just the right moment, too, given that Hillary Clinton all but sealed her nomination in the Democratic contest. The more certain her candidacy appears, the more that mature voices in the GOP have to do to ensure they have a winnable ticket.

Timothy Stanley

But does Kasich, or anyone else, really stand a chance of beating Trump? There are three theories. One is that because he's been denied Ohio's 66 delegates, Trump suddenly has a really hard road ahead to win on the first ballot at the convention. In the coming primaries, the Republicans can beat him the way that a pride of lions kills an elephant -- in small bites that exhaust the beast until it gives in.

The problem with that approach is that it's going to tear the GOP apart. It means several months of bitter fighting, recriminations and -- at the end of it -- Trump could well go third party anyway. Meanwhile, Hillary will be mounting a media blitz against a GOP that seems unfit for government. Kasich, Cruz or AN Other could find themselves stealing a hollow crown.

Theory two is that Kasich winning Ohio is actually good for Trump because it keeps Kasich in the race. If Kasich had lost then the party could have rallied around Ted Cruz, tying up all of the dissident forces into one candidacy -- the stronger candidacy, too, because Cruz has shown an ability to win states other than his own. For a sense of how division has helped The Donald, look at the results in North Carolina and Missouri. There's a strong case for saying that Rubio and Kasich's small but significant showings denied both to Cruz.

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