WASHINGTON — The deadly mass shooting in Las Vegas left Republican-backed bills to loosen gun rules facing an uncertain future.

Before the shooting that killed at least 58 people — the deadliest shooting in modern U.S. history — House GOP leaders had been moving forward with bills to ease regulations on gun silencers and allow those with concealed-carry permits to take their weapons to other states.

Republicans have been upbeat about prospects for legislation as they control both the House and Senate and have an ally in the White House in President Donald Trump. But no votes on either bill were scheduled as of Monday.

Democrats seized on the violence in Nevada to demand tougher gun restrictions, an unlikely scenario as other mass shootings in Colorado, Connecticut, Florida and even attacks on lawmakers failed to unite Congress on any legislative response.

Sen. Chris Murphy, D-Conn., a gun control proponent, said it was "time for Congress to get off its ass and do something." In an outdoor news conference, former Arizona Rep. Gabrielle Giffords, grievously wounded in a 2011 attack, turned to the Capitol, raised her fist and said, "the nation is counting on you."

A Republican-led House committee last month backed the silencer bill by Rep. Jeff Duncan of South Carolina, who said it would help hunters protect their hearing.

Democrats scoffed, noting that the bill also would allow more armor-piercing ammunition. House Democratic leader Nancy Pelosi invoked the shooting of Majority Whip Steve Scalise to oppose the bill last week, saying "if you can hear (a gunshot) you can run" away.

Hillary Clinton tweeted Monday that the crowd in Las Vegas "fled at the sound of gunshots. Imagine the deaths if the shooter had a silencer, which the NRA wants to make easier to get."

Pelosi on Monday asked House Speaker Paul Ryan to create a select committee on gun violence to recommend legislation.

"Today is a day for prayer, mourning and love, but it must also be a day for action," Pelosi said.

Duncan, who grew up hunting with his father, included the silencer measure in a larger bill to enhance hunting and fishing on federal lands. He suffers from hearing loss in one ear as a result of firing guns without earmuffs or suppressors, the term advocates prefer to silencers. The devices muffle the noise of gunshots rather than mute it.

Suppressors generally lower the sound of gunshots by 20 to 35 decibels, leaving most guns still louder than a typical ambulance siren.

Critics say efforts to ease the restrictions will allow more criminals to use them and will make it difficult to detect when and where a shooting is taking place.

A separate bill sponsored by Rep. Richard Hudson, R-N.C., would allow gun owners with a state-issued concealed carry permit to conceal a handgun in any state that allows concealed carry. Hudson said the bill would allow gun owners to "travel freely between states without worrying about conflicting state codes or onerous civil suits."

Democrats called both bills outrageous.

Connecticut Sen. Richard Blumenthal said the Las Vegas shooting shows that, "the time for hand-wringing and soul-searching is over. We need action" on enhanced background checks for gun owners, restrictions on high-capacity magazines and assault weapons, he said.

The shooting is "yet another reminder that nothing has changed since Newtown and the grief and shock we experienced there," Blumenthal said Monday, a reference to the Sandy Hook school shooting in 2012.

Joining Giffords was her husband, retired NASA astronaut Mark Kelly, who said "your thoughts and prayers aren't going to stop the next shooting. Only action and leadership will do that."

Scalise, a Louisiana Republican, called the Las Vegas shooting "an act of pure evil." Scalise returned to the Capitol last week after he was shot and critically wounded in June as he and fellow Republicans practiced for a congressional baseball game.

Scalise encouraged American to donate blood and encourage others to do the same. "In the face of unspeakable evil, our whole nation must respond with countless acts of kindness, warmth and generosity," he said.

Associated Press writer Kevin Freking contributed to this report.