"Hell, yes, we're going to take your AR-15, your AK-47," O'Rourke said in a standout moment at the ABC News Democratic presidential debate Thursday. His comment frustrated some lawmakers on Capitol Hill who are trying to find a way forward on gun legislation that Republicans and Democrats can agree on.

Buttigieg said Sunday he agrees with those who say O'Rourke's comment plays into the hands of Republicans. The South Bend, Indiana, mayor argued now is a "golden moment" to pass gun legislation, telling CNN's Jake Tapper on "State of the Union" that the majority of Americans support so-called red flag laws, banning high-capacity magazines and prohibiting the sale of assault weapons.

"When even this President and even (Senate Majority Leader) Mitch McConnell are at least pretending to be open to reforms, we know that we have a moment on our hands," Buttigieg said. "Let's make the most of it and get these things done."

O'Rourke fired back at Buttigieg on Twitter and wrote, "Leaving millions of weapons of war on the streets because Trump and McConnell are 'at least pretending to be open to reforms'?"

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