Republican Sen. John McCain of Arizona lobbed harsh criticism at his own party on Sunday, arguing presidential candidates who use insulting rhetoric, or fail to correct it, will only wind up helping Democrats in 2016.

The former GOP presidential nominee was asked on CNN’s “State of the Union” about front-runner Donald Trump, who recently came under fire for staying silent at one of his rallies when a supporter incorrectly declared President Obama is a Muslim and “not even an American.”

The exchange was reminiscent of one McCain had with a woman at a 2008 rally in Minnesota, in which he corrected her for calling Obama “an Arab.”

“I think we are hurting ourselves and our chances to win the general election,” said McCain. “If we disparage each other and impugn character of each other, then after the primary is over obviously there’s a trust and support deficit among the American people.” While he didn’t name check any of the candidates, McCain said candidates have a responsibility to correct and condemn bigotry.

Related: Sen. McCain: This is a very sad day for America

Separately, McCain did take a hit at Trump, arguing the real estate mogul doesn’t understand the escalating situation in Syria. Russia recently launched strikes in the country, insisting it is targeting the terrorist groups known as ISIS. U.S. officials, however, are skeptical and believe Moscow is going after U.S.-backed rebels in hopes of propping up Syrian President Bashar Assad’s regime.

“I don’t think he understands very well the situation. He’s entitled to his opinion,” McCain said of Trump.

Trump recently argued the U.S. should not get involved, saying, “Let Syria and ISIS fight. Why can’t we let ISIS and Syria fight? Let Russia, they’re in Syria already, let them fight ISIS. Let Russia take care of ISIS. How many places can we be?” he asked.

McCain (who has called for a no-fly zone in Syria, which the Obama Administration doesn’t support) criticized Trump’s argument. “Do we want to keep slaughtering people in Syria that are fighting for freedom?” McCain asked. “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?” he added.