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Sen. John McCain questioned Donald Trump's understanding of Syria on "State of the Union" Sunday

McCain said Republican presidential candidates' tones have hurt the party

Washington CNN  — 

Sen. John McCain says that GOP presidential front-runner Donald Trump doesn’t understand the problems posed by Russia’s new role in the Syrian conflict.

“I don’t think he understands very well the situation. And he’s entitled to his opinion,” the Arizona Republican said Sunday in an interview with CNN’s Jake Tapper on “State of the Union.”

McCain was pushing back against Trump’s assertion last week that the United States should let ISIS and Syria’s army fight – and let Russia worry about ISIS there. Trump’s comment came as Russia launched air strikes in the region.

“Do we want to keep slaughtering people in Syria that are fighting for freedom?” McCain said. “Do we want to continue the barrel bombing, which is one of the reasons why 240,000 Syrians have been murdered? Do we want this flood of refugees to continue?”

In the interview, McCain also prodded Republican presidential candidates to “think about Ronald Reagan and the way he conducted his campaigns.”

“To impugn each other’s characters and integrity is very harmful to each other, ourselves, and our chances of winning a general election,” he said, without naming any specific candidates.

“I think there’s a lot of people in the party that are not happy about the tenor of some of the remarks and the allegations about each other,” McCain said. “I’m afraid we will pay a price for it at the polls, and I hope we’ll change.”