(CNN) Republican National Committee Chairman Reince Priebus said Sunday that no matter the convention-floor machinations, the GOP nominee will be one of its three current presidential candidates.

"Our candidate is someone who is running," Priebus said in an interview with CNN's Jake Tapper on "State of the Union."

He downplayed the possibility of an alternative like House Speaker Paul Ryan emerging after several ballots in a contested convention in Cleveland.

"Here's the thing: If anything like that were to happen, which I think is highly, highly, unlikely -- I think our candidate is someone who's running, OK? That's pretty obvious -- but No. 2, even if something like that were remotely possible, that candidate would actually have to have a floor operation and an actual campaign going on with the delegates to make something like that possible, and Paul's not going to do that," Priebus said.

As for Ryan, Priebus said, "He doesn't want to do it. I know Paul very well."

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