There’s growing consensus that the best a fractured field can do to stop Trump is to win enough delegates to prevent him from clinching the nomination, forcing a contested convention. That scenario — only an option because so many candidates are still in the race — hinges on whether Trump or the rest of the candidates combined can reach the needed 1,237 delegates first.

After 15 contests, including a very successful Super Tuesday for the billionaire, Trump and the rest of the field are running nearly even. What is becoming clear is that going into the convention in July, either Trump will be the Republican nominee (most likely), or no one will be. If it’s the latter, delegates would likely take part in multiple rounds of voting to select a nominee. Here’s a look at the road ahead.