A top Republican National Committee official believes Sen. Ted Cruz (R-Texas) would run for president in 2020 even if Donald Trump is the sitting president.

“If Trump wins, you better bet your ass Cruz is going to primary him,” an unnamed RNC official told Yahoo News.

{mosads}Cruz faced off with Trump in a bitter GOP presidential primary this year, eventually ending his campaign after losing the Indiana primary in May.

The Texas senator has not yet endorsed Trump but has accepted a speaking slot for the Republican National Convention’s Wednesday night session.

Hours before Cruz was scheduled to speak, he held a thank-you event for his delegates and supporters in Cleveland. At the event, any mention of Trump drew loud boos from his supporters.

Attendees also chanted “2020” during the event.