In an effort to stop Donald Trump from getting the Republican nomination, Marco Rubio encouraged supporters to back John Kasich in the Ohio primary.

"Face the Nation" anchor John Dickerson said this is the plan for those who don't want Trump to be the nominee -- deny him the delegates he needs in order to make it to a contested convention.

"It's what Mitt Romney called for explicitly," Dickerson said. "But it's taken nine days for Senator Rubio to endorse it."

Dickerson also discussed Trump's relatively calm demeanor in the most recent GOP debate, compared to his combative and sometimes crass behavior in the previous matches.

"He's trying to close the deal. He's talking about unity, talking about his flexibility, to calm those in the Republican party who have been nervous about his nomination," Dickerson explained.

"In real estate they call it the 'good cop, bad cop' negotiation. Trump is playing both parts."

To hear what else Dickerson has to say about the GOP race, watch the video above.