Speaking at a National Rifle Association meeting in Charlotte, N.C., Gingrich pointed out Kagan tried to bar military recruiters from the Harvard Law School campus when she was the dean there, The Charlotte Observer reported Sunday.
"That is an act so unbecoming an American that she should be disqualified," Gingrich said.
Speaking with conservative commentator Glenn Beck, the rally in advance of mid-term elections in November included jabs at the "Marxist revolutionaries" in the Obama White House, the newspaper said, attributing the phrase to both Beck and Gingrich.
"We have to think of something because the Titanic is going down. We need to save the passengers, that's what we need to worry about," Beck said.
About 10,000 spectators attended the event, while about 10 protested outside carrying signs reading, "NRA Lax Gun Laws Kill" and "End the Gun Show Loophole," the newspaper said.
There were sporadic arguments between spectators and protesters.
"I'm fighting for American lives," said Abby Spangler, a member of Protest Easy Guns, a Washington, D.C., group.
"I've had a gun for 43 years and I've never killed anyone," Rae Ann Effinger of Pennsylvania shouted at the protesters.
"These people are ridiculous," Effinger shouted.