Yes, Barack Obama said, "If they bring a knife to the fight, we bring a gun," on June 13, 2008, during a campaign fundraiser in Philadelphia while running for president. [1, 2, 3]
"I need ya to go out and talk to your friends, and talk to your neighbors. I want you to talk to 'em whether they are independent or whether they are Republican. I want you argue with them, and get in their face