Democrats took to the floors of the Senate and House on Tuesday to draw attention to their drive to prevent suspected violent extremists from obtaining guns, an issue they believe has gained potency from last week's shooting massacre in California.

Facing certain defeat, Democrats in both chambers unsuccessfully tried forcing votes on legislation that would let the government prohibit firearms sales to people suspected of terror acts. Debate, livid at times, came days after a Muslim couple who federal authorities say adopted extremist views killed 14 people last week in San Bernardino, California.

Sen. Chuck Schumer, D-N.Y., called it "absolute insanity" that suspected violent extremists are not already among the categories of people barred from purchasing firearms from gun dealers. Without naming them, he blamed the gap on the National Rifle Association, which for years has used an alliance with gun-rights lawmakers, mostly Republicans, to block gun control legislation in Congress.

"We can't let a small group, an influential, powerful lobbying group, make Americans less safe," Schumer said.

No. 2 Senate Republican leader John Cornyn blocked debate on the legislation, which is sponsored by Sen. Dianne Feinstein, D-Calif., a longtime advocate of gun curbs.

He offered his own plan giving the government 72 hours to delay gun sales to those suspected of terror acts and persuade a judge to block that sale, and letting the government immediately arrest the suspect. Democrats blocked that.

Cornyn said Democrats were trying to "capitalize" on last week's California shootings "to justify this unconstitutional attempt to deny American citizens their core constitutional rights," such as gun ownership.

The Senate last week rejected Feinstein's proposal and a Cornyn proposal similar to Tuesday's.

Republicans have reacted to the San Bernardino killings by emphasizing national security, pushing legislation stiffening restrictions on refugees and travel to the U.S.

In the House, Democrats led by Rep. Mike Thompson, D-Calif., a leading gun control advocate, forced a series of procedural votes to protest GOP leaders' refusal to allow debate on legislation by Rep. Peter King, R-N.Y., that is similar to Feinstein's.

Rep. Scott Perry, R-Pa., drew boos and catcalls from Democrats when he railed against the "fool's errand" of their push for a gun control vote.

"They have no idea what it takes to get on the no-fly list," Perry said. He said that list is maintained by "the same administration that persecutes its citizens" with the Internal Revenue Service, a reference to the 2013 outcry over that agency's intense scrutiny of some conservative groups seeking tax exemptions.

"We're just asking for terrorists not to be able to walk into a gun shop and buy a gun," said Rep. Sheila Jackson Lee, D-Texas.

Thompson is circulating a petition he hopes would force debate on King's gun measure. That petition effort is likely to fail.

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AP reporter Donna Cassata contributed to this report.