Mitt Romney has declined to call on his supporters to stop heckling President Barack Obama's campaign.

He told Fox News Radio on Tuesday that he doesn't believe in "unilateral disarmament," but said it would "be a nice thing" if both sides would stop yelling at each other during campaign events.

Over the weekend, Obama adviser David Axelrod condemned anti-Romney heckling during the Republican candidate's bus tour, which ends Tuesday in Michigan.

Romney was asked if he would also condemn heckling during Obama events. He declined.

Responding to Romney later Tuesday, the Obama campaign said it had sent a strong message to its supporters that the campaign should be about an open exchange of ideas, not drowning out the other side by heckling and crashing events.

"Campaigns are a reflection of their candidate," said Ben LaBolt, the Obama campaign's spokesman. "Mitt Romney has a different view, endorsing heckling."

Axelrod was heckled aggressively by Romney supporters during a news conference last month in Boston. Romney supporters also regularly drive a campaign bus around to Obama events and honk the horn repeatedly.

Romney said Tuesday that American politics has a "long history of heckling and free speech."