Speaker Mike Johnson may not have a functional majority in Congress, but his job is similar to the Republicans who preceded him in at least one respect: The duties include the difficult task of managing Donald J. Trump.

Mr. Johnson on Friday will travel to Mar-a-Lago, Mr. Trump’s Florida estate, to join him for what the speaker has billed as a “major announcement on election integrity.” No further details have been forthcoming.

The two men had been planning to get together for a political meeting, but Mr. Johnson’s team suggested a joint public appearance on a topic Mr. Trump cares deeply about, according to two people familiar with the planning.

It will afford Mr. Johnson the opportunity to stand shoulder to shoulder with Mr. Trump at a precarious moment in his speakership, as he works to corral a minuscule and deeply divided majority around a legislative agenda many of them oppose — all while facing the threat of an ouster from Representative Marjorie Taylor Greene, a far-right Georgia Republican and ride-or-die Trump ally. Making matters even trickier, Mr. Trump, the former president and presumptive Republican presidential nominee, is helping to undermine that agenda.

Even so, Republicans generally consider it good and politically helpful to be physically near Mr. Trump.

“It’s about Trump embracing Johnson,” former Speaker Newt Gingrich said of Friday’s joint appearance. “This is Trump saying, ‘He is the speaker, I am his friend, we are together.’ That’s a pretty important thing for him. He just has to endure.”

Mr. Trump does think of Mr. Johnson, who defended him in two impeachment trials and played a key role in his efforts to overturn the 2020 election, as something like a friend, people close to him said. He likes the Louisiana Republican, and likes his loyalty even more. (He especially appreciated that Mr. Johnson quickly endorsed him after becoming speaker, a move that his predecessor Kevin McCarthy always resisted). The two speak regularly, and Mr. Trump has even come around on some of the congressional endorsements Mr. Johnson has lobbied him on.

Still, if this is what an embrace looks like, it’s not clear that it’s so much better than the alternative.

Mr. Trump earlier this week weighed in against legislation that Mr. Johnson put forward to extend an expiring warrantless surveillance law that national security officials say is crucial to fighting terrorism and gathering intelligence. Mr. Trump urged lawmakers to “kill” the law undergirding the program, and ultraconservatives in the House banded together to block it from coming to the House floor in an embarrassing defeat for Mr. Johnson.

The speaker was set on Friday to try again to push the measure through the House, just before boarding a plane for his audience with Mr. Trump.

The former president has also said it is “stupid” for the United States to send aid to Ukraine and railed against doing so, even as Mr. Johnson has made it clear that it is a top priority of his to bring up a bill to provide an infusion of American military assistance to Kyiv.

The dynamic means that even as they present a united front at Mar-a-Lago, the pair will be at odds on many issues they could be asked about. Such is life with Mr. Trump. And for Republican speakers, it always has been.

For a short time after Mr. Trump first arrived in the White House in 2017, he deferred to Republican leaders on Capitol Hill on their legislative efforts, which included trying to repeal Obamacare and seeking tax cuts. Former Speaker Paul D. Ryan, who had refused to campaign for Mr. Trump, benefited from the fact that the new president had a personal interest in the success of a shared Republican agenda.

Even so, managing the relationship required both hand-holding and hand-wringing about who was going to be the last person in Mr. Trump’s ear. In 2018, for instance, Mr. Trump threatened to veto a big spending bill that had been approved by Congress. Mr. Ryan had to work to convince him to sign it.

“It would be these fire drills where you had to send five or six people to walk him back,” recalled Brendan Buck, who served as a top adviser to Mr. Ryan. “You’re always going to be fighting the last person who talked to him, emotional whims, the thing he read. It’s a constant battle you always have to be fighting.”

That same year, Mr. Trump almost scuttled a version of the surveillance legislation he tanked this week when he tweeted criticism of it — breaking with his administration — apparently after watching a segment on Fox News. “Everyone was calling him, the national security adviser rushed over, people were rushing over to the White House,” Mr. Buck recalled. Mr. Trump eventually walked back his post 90 minutes later.

But Mr. Trump now has less of a stake in the Republican agenda in Congress — it’s not his. And he is not surrounded by a national security apparatus that can weigh in and help keep him on a track that is more in line with that of party leaders in Congress.

As he settled into the White House, Mr. Trump also started keeping his own counsel more and relying less on congressional leaders for direction. He was not interested in taking Mr. Ryan’s advice, for instance, about trying to avoid a government shutdown at the end of 2018.

Mr. McCarthy spent years nurturing his relationship with Mr. Trump, going so far as to sort out his favorite flavors of Starburst to curry favor. He visited the former president at Mar-a-Lago after the Jan. 6, 2021, mob attack on the Capitol in an attempt to smooth over any divisions.

Mr. McCarthy had an up-and-down relationship with Mr. Trump during his short tenure as speaker. He succeeded in steering some of Mr. Trump’s endorsements during the 2022 midterm campaigns, and his biggest win might have been keeping the former president silent during his negotiations with the White House over the debt ceiling — Mr. Trump waited until after the deal was signed to criticize it.

Mostly, Mr. McCarthy benefited from timing: The former president was not yet the presumed Republican nominee during his tenure and was less involved in the agenda in Washington.

Mr. Johnson may have the worst of both worlds: Mr. Trump is not the president, so he does not have a shared interest in the Republican speaker’s legislative success, but at this stage of the presidential campaign, he is attuned enough to potentially complicate anything he tries to do. Mr. Trump continues to carry enough influence with Republicans on Capitol Hill that his opposition can be enough to sink a bill outright, and Mr. Johnson has not had as long to cement their relationship.

“Johnson has the hardest speakership of anyone since maybe the beginning of the Civil War,” Mr. Gingrich said. “His major goal has to be to hold the system together to get to an election in which Trump increases Republican turnout.”

People close to Mr. Trump said he values Mr. Johnson’s political insights and has deferred to him at times on endorsements. Mr. Johnson lobbied him hard to back Representative Mike Bost, Republican of Illinois, over Darren Bailey, a competitive challenger running a spirited MAGA campaign. It was a difficult endorsement for Mr. Trump to come around to, people familiar with it said, but he ultimately did so at Mr. Johnson’s urging.

Ms. Greene, for her part, said she would not back down on her criticism of Mr. Johnson or drop the threat to try to oust him, even if Mr. Trump gives the speaker a public boost.

“Things like that don’t bother me,” she said of Mr. Trump hosting an event with Mr. Johnson. Of the speaker, she added: “Right now, he does not have my support.”