David M Jackson

USA TODAY

Paul Ryan is hoping Donald Trump really does elevate the tone of his campaign, but otherwise seems prepared to (again) criticize the presumptive Republican presidential nominee if necessary.

"When anyone in our party, least especially our nominee, says things that run contrary to our beliefs, to our values, to our principles, we have an obligation to call them out," Ryan said on CBS' Face The Nation. "We have an obligation to not support those things because they don't define who we are."

Ryan, who endorsed Trump earlier this month, spoke less than a week after criticizing the New York businessman for saying a federal judge may be biased against him because of "Mexican heritage." The House speaker described Trump's comments as the "textbook" definition of racism.

He told CBS he is "kind of learning as I go" when it comes to Trump.

"I believe in this job I have as speaker of the House that it is important that I help unify our party so that we're at full strength in the fall so that we can win an election," Ryan said.

Trump backers, meanwhile, have described Ryan as the personification of the Republican establishment they said they are fighting.

In a column for Breitbart News — one tweeted out by a Trump staff member — Trump backer Wayne Allyn Root urged the presumptive nominee to "ignore" Ryan.

"He’s the old guard," Root wrote. "He’s a loser. He’s another Mitch McConnell. He’s the new John Boehner. Paul Ryan is the reason the GOP is losing America."