There has been a whole lot of talk about how Republicans who allegedly want to prevent Donald Trump from being their nominee might try to exploit the possibility of a contested convention, i.e. if none of the four remaining candidates (but really only two have a shot: Trump and Ted Cruz) meets the threshold of 1,237 party delegates needed to win the nomination.
At the Guardian, Ben Jacobs has a solid piece explaining how that all works, for anyone who has questions about the process.
I really don't think it's going to come to that. I expect that Trump will either win the nomination outright, or come so close that it would be absurd for the Republican Party to try to undermine him and their base.
The Republican Party does a lot of absurd things, but essentially conceding they don't even want to try to win the presidency, and risk their Congressional majorities in the process, is highly unlikely to be one of them.