Story highlights "What's a lifelong Republican supposed to do, support the opponent? I don't think so," Dole said

Dole said he believes Trump still has time to win over women, minorities and other groups

Washington (CNN) Bob Dole encouraged fellow Republicans Saturday to back Donald Trump and suggested the presumptive GOP nominee select Newt Gingrich as his running mate.

In an interview with CNN's Ana Cabrera, Dole -- the 1996 Republican nominee who said he spoke with Trump last week -- also suggested Trump apologize to Arizona Sen. John McCain and New Mexico Gov. Susanna Martinez for disparaging comments he's made about them in the past.

"I have been a Republican all my life," said Dole, who endorsed former Florida Gov. Jeb Bush at one point during the 2016 primary fight but has since backed Trump. "The party has done a lot for me. I hope I've done a lot for the party along the way. But when Donald Trump clinched the Republican nomination, it was an easy call for me. What's a lifelong Republican supposed to do, support the opponent? I don't think so."

Asked about notable Republicans who haven't yet supported Trump -- including Bush and House Speaker Paul Ryan -- Dole said, "Well, they still have time to get on the train. It's not moving that fast right now."

Dole pointed out that at one time, Bush had said he would support the GOP nominee, regardless of who it was.

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