Only a few weeks ahead of the Republican National Convention, Donald Trump is preparing for what’s likely to be a charged event, as some Republicans look to upend the gathering. How? The Republican National Committee and the Trump campaign are threatening to keep those who are not in favor of the party’s nominee from taking speaking slots at the gathering, according to The New York Times.

It’s the culmination of a heated primary season that began with 17 Republican presidential candidates and that, over time, narrowed, as Trump swept states across the nation. And right now, it’s unclear if some of those who exited the race will be permitted to speak at the convention, given Trump’s conditions. Take Senator Ted Cruz: He dropped out of the race in May, and he still has not endorsed Trump. But as the Times notes, however much Trump may want to bar the Texas senator, it may not be possible for him to keep Cruz from speaking. That’s because, since Cruz “won a majority of delegates in at least eight states, he would probably be able to have his name entered into nomination, guaranteeing him a speech under party rules.”

Another former primary rival, Ohio Governor John Kasich, has said he isn’t prepared to back Trump. But barring Kasich from speaking at the convention bears particular significance, as he’s the governor of the state where the convention is taking place. Nevertheless, Trump made clear in an interview with the Times that without their backing, he has no intention of letting Kasich or Cruz appear. “If there’s no endorsement, then I would not invite them to speak,” Trump said.