WASHINGTON — For two decades, through Columbine, Virginia Tech, Newtown, Orlando, Las Vegas and the rest, mass shootings have provoked only scant action in Congress. Now, after horrific back-to-back massacres this weekend, people in both parties agree that one man could change that: Senator Mitch McConnell.
As President Trump urged national unity in the face of “racist hate” without endorsing broad gun control measures, Democrats and a handful of Republicans called on Monday for Mr. McConnell, the majority leader, to bring up legislation to require gun buyers — including those on the internet and at gun shows — to go through background checks.
Mr. McConnell, nursing a fractured shoulder from a weekend fall at home in Kentucky, made no commitments. After consulting with advisers and fellow Republicans, he issued a statement Monday evening saying that he had asked three top committee chairmen “to engage in bipartisan discussions” about how to address gun violence “without infringing on Americans’ constitutional rights.”
“Senate Republicans are prepared to do our part,” he said.
But just what “our part” is, was unclear. One of Mr. McConnell’s longtime advisers, J. Scott Jennings, said Monday that Mr. McConnell was positioned to lead a process in Congress that could “achieve a solution that, at a minimum, comforts the nation.”
“People want something to happen,” he said. “I don’t think people want mass confiscation of guns, but they do want something to show responsiveness.”
With Congress in recess, Speaker Nancy Pelosi and Senator Chuck Schumer, the Democratic leader, demanded that Mr. McConnell bring back the Senate — something he is highly unlikely to do — to consider a House background checks bill, which passed in February.
While some House Democrats want Ms. Pelosi to call back the House to consider additional legislation, such as an assault weapons ban, Democratic leaders want to keep the pressure on Mr. Trump and Mr. McConnell. After a conference call with House Democrats on Monday, Ms. Pelosi sent them a “Dear Colleague” letter saying two committees would hold hearings on domestic terrorism and gun violence.
“The president and Mitch McConnell have to feel the public sentiment on this,” Ms. Pelosi told Democrats during the call, according to an aide. “We have a golden opportunity to save lives.”
In the Senate, some of Mr. McConnell’s Republican colleagues were speaking up.
Senator Susan Collins of Maine, who faces a tough re-election race next year if she runs again, said she had “long supported closing loopholes in background checks.”
Senator Mike Braun, a freshman from Indiana, said any bipartisan legislation to address gun violence must include stronger background checks and “red flag” laws, which were cited by Mr. Trump and would allow the temporary confiscation of firearms from people deemed a danger to themselves or others.
Senator Lamar Alexander of Tennessee, one of the committee chairmen called into action by the majority leader, vowed, “I am ready to do more, especially on background checks, to identify those who shouldn’t have guns.”
And Senator Patrick J. Toomey of Pennsylvania convened a conference call with reporters to announce that he was reviving his background check measure, which failed in the Senate in 2013. He said he spoke Monday morning to Mr. Trump, who expressed “a very constructive willingness to engage on this issue,” and also to Mr. McConnell, whose comments he would not characterize.
“My view is, if we have enough support in the Senate, then we ought to have a vote, and I intend to do everything I can to persuade Senator McConnell if that’s necessary,” he said. “It’s important to me that we get that vote.”
At 77, Mr. McConnell, who is running for re-election in 2020, has cast himself as the “grim reaper” for liberal legislation. Ms. Pelosi and Mr. Schumer have repeatedly called the Senate a “legislative graveyard,” and around the country, Mr. McConnell has become a target for liberals — as reviled by the left as Ms. Pelosi is on the right.
On Monday, he was being pilloried on social media with the hashtag #MassacreMitch — a twist on #MoscowMitch, the moniker that critics used to assail him for blocking election security legislation. His campaign came under attack for tweeting a photograph of a mock graveyard depicting tombstones with the names of Merrick B. Garland, whose Supreme Court nomination Mr. McConnell blocked, and Amy McGrath, his likely Democratic opponent.
The McConnell campaign said it did not produce the gravestones, which were photographed at Fancy Farm, a Kentucky political picnic, as a spoof of a newspaper cartoon that Ms. McGrath herself had circulated. But Ms. McGrath upbraided the campaign for “nasty and personal” attacks — a message that was picked up by Gabrielle Giffords, the former congresswoman who was grievously wounded in a mass shooting in Tucson in 2011, and is now an advocate for gun safety laws.
“I am appalled that in this divisive political climate — a climate where gun violence fueled by hate is on the rise — Mitch McConnell is joking about the death of his current and former opponents and a federal judge,” Ms. Giffords said in a statement. “The nation is turning to Leader McConnell right now for leadership, and this is the furthest thing from it.”
Gun violence — and how to address it — has been one of the most intractable and divisive issues in Washington; the last time the lawmakers voted to restrict gun ownership was 1994, when Congress passed an assault weapons ban.
Even gun control advocates acknowledge that this weekend’s mass shootings in Texas and Ohio are unlikely to produce quick congressional action. Still, some Republican strategists say they sense a shift in sentiment in their party.
“There clearly seems to be a consensus developing on both sides of the aisle for universal mandatory background checks,” said Whit Ayres, a Republican strategist. “And the door may be opening a bit more for a ban on military-style assault weapons and magazines.”
With the National Rifle Association, the nation’s most powerful gun lobby, in disarray amid a string of lawsuits and internal upheaval, some Republicans who favor tightening gun laws say now is the time to act.
But Mr. McConnell, who wants to maintain the Republican majority in the Senate, is well aware that voters in rural hunting states — including his own — would not look kindly on any restrictions on gun rights. Al Cross, the director of the Institute for Rural Journalism and Community Issues at the University of Kentucky, said Mr. McConnell was unlikely to push for them.
“Six words,” Mr. Cross declared. “We love our guns in Kentucky.”
And Mr. McConnell is unlikely to act without the approval of Mr. Trump, whose own statements on gun violence have been all over the place. In an early morning tweet on Monday, Mr. Trump called for “strong background checks,” but tied them to an immigration law overhaul. In a speech from the White House a few hours later, he did not mention background checks, but instead called for red flag laws.
Conservatives quickly seized on the idea. Senator Lindsey Graham, Republican of South Carolina and a close ally of Mr. Trump, said after the speech that he and Senator Richard Blumenthal, Democrat of Connecticut, had agreed on a plan to use federal grants to help states enact red flag laws. He said he had spoken with the president about the proposal, “and he seems very supportive.”