WASHINGTON — He has called Senator Christopher S. Murphy, a Democrat from Connecticut, where 26 people were gunned down at an elementary school. He has reached out to Senator Joe Manchin III, Democrat of West Virginia, and Senator Patrick J. Toomey, Republican of Pennsylvania, who sponsored a bill extending background checks that the Senate defeated in 2014.
What President Trump has not done yet is the kind of arm-twisting of Republican senators wary of gun control legislation that will be necessary to force a bill through Congress, according to interviews with White House officials and congressional aides. He has shown no interest so far in a major address to ensure that public opinion is behind such a move. And he and his aides have yet to settle on what he will actually propose.
But they have commissioned a poll through his campaign to assess where his supporters are on different gun control measures, and they will have the results by September, when the Senate returns from summer recess, according to three people briefed on the plans.
Until that happens, the discussion inside the White House about what, if anything, to do about new gun measures — and Senator Mitch McConnell, the majority leader, has warned that it will have to be the president who calls Republicans to action — is largely theoretical.
The aftermath of the back-to-back massacres in El Paso and Dayton that killed 31 people has created an opening for Mr. Trump, who has been encouraged by advisers that he could accomplish something that his predecessors were unable to, and who has told reporters that he wants to accomplish “meaningful background checks.” And the president has assured advisers that he thinks the powerful National Rifle Association, which is rife with internal conflict, is “going bankrupt.”
But Mr. Trump is still facing pushback from gun rights advocates and some of his own advisers, and in the end, the president could repeat his pattern on other issues of abruptly dropping the idea of doing something after talking about it for weeks.
“He has to do some of the Lyndon Johnson ‘come, let us reason together,’ real down-to-earth stuff that Johnson did,” said Senator Richard Blumenthal, a Connecticut Democrat who is a leading proponent of gun safety, invoking the former president and onetime Senate majority leader who was famous for leaning on lawmakers — not only figuratively but sometimes physically — to get the legislation he wanted.
“If Donald Trump is standing there,” Mr. Manchin said, “and we’ve got bipartisan senators standing beside him, and he says, ‘This is my piece of legislation and I support it wholeheartedly,’ it’ll pass. Without that, we’re back to square one.”
A White House spokesman did not respond to a request for comment.
But Mr. Trump told advisers shortly after the shootings less than two weeks ago that he wanted to put in place some type of measure restricting who could buy guns. And aides privately anticipate that he will try to convince senators who are uncertain about backing legislation related to guns once the Senate returns to Washington.
But they are less convinced that Mr. Trump will need to make a public push to sell the public on the wisdom of the move.
Led by Joe Grogan, the director of the Domestic Policy Council, and Eric Ueland, the White House legislative affairs director, the president’s advisers are looking into possible changes in federal law. They include mandating the death penalty for mass shooters, and what, if any, role violence in entertainment plays in encouraging mass shootings and what the federal government might do about it.
They have also been instructed by the president to examine options beyond legislation, including programs to help law enforcement identify people who are dangerous.
Recognizing that the president’s own aides may try to steer him away from action, Mr. Manchin sought to remind them who is in charge by noting that his conversations with the president and his advisers made it clear that the staff members are “under strict orders to get something accomplished.”
In recent days, Mr. Ueland, who joined the White House in June as Mr. Trump’s chief legislative liaison, has been hosting meetings with aides to various senators interested in gun safety legislation, including Mr. Manchin and Mr. Toomey, according to two officials familiar with the talks.
Those talks have centered on two possible paths: “red flag” laws, which make it easier for the authorities to take guns away from those deemed dangerous by a judge, and bills that extend background checks for gun buyers, which currently do not apply to private sales at gun shows or over the internet.
So far, the White House has not committed to any specific measures, the officials said, but added that Mr. Trump would not back a House bill, passed in February, extending background checks to all gun buyers. Republicans, including Mr. Toomey, view that measure as too expansive. The House bill requires background checks on nearly all purchases, with limited exceptions for sales between friends and family members, while Mr. Toomey’s requires checks only on commercial sales.
But Mr. Trump has said for the past week that he wants to expand background checks and that Mr. McConnell is in favor of that as well.
Mr. McConnell, who is seeking re-election in the gun-friendly state of Kentucky, has never said that; he has simply said the issue of background checks will be “front and center” in a coming Senate discussion on how to prevent gun violence. And he has not committed to a vote on a background check bill.
In private conversations with Mr. Trump, Mr. McConnell has bluntly told the president that he will back such a move if the Republican Senate conference does, but that it is Mr. Trump who will have to nudge senators to support it.
Adding to the uncertainty is the reality of Mr. Trump’s White House, where advisers are not always operating from the same playbook.
Mr. Manchin and other senators pressing for action on guns are counting on Ivanka Trump, the president’s eldest daughter and senior adviser, to keep Mr. Trump from bowing to pressure from the N.R.A. and Republican hard-liners in Congress to not take any actions on guns.
“I think she can — her and the family, but especially her — can be the buffering when the pushback comes,” Mr. Manchin said. “She can tell him, ‘Let’s stay strong; let’s stay true. We know we’re solid with Republicans, with the base.’”
But the involvement of Ms. Trump has prompted unease among some Republican senators, who worry that having someone whose own father privately calls her a liberal as the face of the effort could hurt them in their own states.
Scott Jennings, a Republican strategist who is close to Mr. McConnell and has encouraged him to take up gun safety legislation, said it was “vital” for Mr. Trump to talk to senators directly about measures “that he feels are consistent with his party’s and his own personal values when it comes to guns” and to then lay out an agenda that he can accept.
“This will fly if the president can get behind a package that he can sign into law,” Mr. Jennings said, adding, “It’s for the president to define for the Republican Party what direction policy is going to take.”