"He's doing a really good job under very tough circumstances," Trump said at the start of a press conference with Johnson at his Mar-a-Lago resort in Florida.
Johnson gained the speaker's gavel in a weeks-long October nominating battle after a handful of House Republican hardliners orchestrated the ouster of his predecessor, Kevin McCarthy, a historic first.
Another party hardliner, Representative Marjorie Taylor Greene, has threatened to make a similar move against Johnson if he allows a vote on more aid for Ukraine as it struggles to fight off a Russian invasion. Greene had also voiced opposition to a surveillance bill the House passed on Friday.
The appearance at Trump's Mar-a-Lago Florida resort with the Republican presidential candidate could help buck up Johnson's standing with his 218-213 majority. His own members have repeatedly torpedoed his legislative priorities, including this week by temporarily blocking the surveillance bill and in February, when it took two efforts to advance a bid to approve articles of impeachment against Democratic President Joe Biden's top border official, Homeland Security Secretary Alejandro Mayorkas.
Trump, who holds great sway with congressional Republicans, has also regularly weighed in on legislation, including killing a bipartisan U.S.-Mexico border security deal, passage of which could have weakened one of his key attacks against Biden.
The meeting presented Johnson with a chance to show a united front with the former president that Republicans say is necessary if the party is to retain control of the House and capture both the Senate and the White House in November.
"We've got to get on the same page about where we want the party to go," said Representative Kevin Hern, who leads the conservative Republican Study Committee, the biggest House Republican caucus.
"I don't think we've all heard directly how the president and the speaker are aligned," Hern added. "We've got to get in lockstep as the Republican Party."
Greene this week has repeated her threats to force a vote to remove Johnson from leadership.
"Our voters will not support a Republican Party that continues like his leadership has been," Greene told reporters after a meeting with Johnson on Wednesday. "We have to have changed behavior that supports the policies that the American people are supporting under President Trump."
Disorder within the caucus has repeatedly forced Johnson to use a parliamentary maneuver bypassing Republican hardliners and relying on substantial Democratic support to pass critical legislation, such as bills averting government shutdowns.
But strong support from Trump could neutralize Greene's ouster threat and spare a repeat of the chaos that ensued after McCarthy's ouster.
Trump could also determine which path the speaker takes on Ukraine aid, despite appeals to approve the assistance from an unprecedented number of foreign leaders.
"As far as being able to move anything in the House, his support or lack thereof is actually incredibly impactful," Republican Representative Kelly Armstrong said.
