By James Oliphant and Amanda Becker
DES MOINES, Iowa (Reuters) - Democratic presidential contenders urged Congress on Saturday to take action to curb gun violence in the wake of mass shootings last weekend in Texas and Ohio that left 31 dead.
Speaking at a hastily convened forum in Iowa, they called for the imposition of universal background checks on gun buyers, so-called "red flag" laws, and ultimately a ban on military-style assault weapons.
They also said they believed the long-standing debate on gun violence in America was shifting in favor of stronger restrictions.
"We are going to make change. We are going to pass gun safety laws in this country," said U.S. Senator Elizabeth Warren of Massachusetts.
"The heat's been on like it's never been on before," said fellow Senator Amy Klobuchar of Minnesota.
The candidates took questions from gun-control advocates and shooting survivors at a program sponsored by Everytown for Gun Safety, an advocacy group founded by former New York Mayor Michael Bloomberg.
In the shootings in El Paso, Texas, and Dayton, Ohio, the gunmen used semi-automatic weapons with high-volume magazines.
Pete Buttigieg, the mayor of South Bend, Indiana, called for those weapons to be taken off the streets.
"They have no basis in our neighborhoods in peacetime in the United States of America," Buttigieg said.
Warren said if she wins the White House she would use executive powers to impose increased background check requirements and more reporting on multiple gun purchases, and expand age restrictions to limit teenage access to guns.
She said she would also push to do away with the filibuster, which would allow gun legislation to pass the Senate by a simple majority vote.
Iowa is a key focus of campaigning because in February the state will hold the first nominating contest in the Democratic presidential primaries ahead of the 2020 presidential election.
Many have called for measures such as an assault weapon ban, universal background checks and other gun control reforms long stymied by partisan fighting in Washington.
Democrats have criticized Republican President Donald Trump's mixed messaging this week on possible support for some gun control measures.
Trump on Friday suggested that he could sway the nation's powerful gun lobby, the National Rifle Association, to drop its opposition to gun restrictions.
Klobuchar suggested Trump would not stand up to the group, however. "We have a guy in the White House who is afraid, afraid of the NRA," she said.
She and others also criticized Senate Majority Leader Mitch McConnell, a Republican, for refusing to bring a background check bill and other legislation to the floor for a vote.
U.S. Senator Bernie Sanders of Vermont called on McConnell to immediately reconvene the Senate, which is in recess for a month, to debate gun legislation.
Former Vice President Joe Biden, the current Democratic frontrunner, touted his work in the Senate in the 1990s passing an assault weapons ban that has since expired.
"I’ve taken on the NRA nationally, and I’ve beaten them," Biden said.
"Red flag" laws would allow the police to temporarily confiscate guns from people deemed by a judge to be a threat to themselves or others.
Candidates also want to close the so-called "boyfriend loophole," which permits convicted domestic abusers to continue to purchase firearms if they were not married to their victims.
Media magnate Bloomberg has pledged to use his well-funded political action committee in next year's elections to defeat candidates who resist gun-reform legislation.
If the current push for new restrictions fails, as has happened in the past, Bloomberg said, “We have make sure all those who stood in the way face the consequences.”