Deepening a fissure that destroyed his first major effort to pass a law, Trump took aim at members of the so-called "Freedom Caucus," branding them as a foe in the same vein as Democrats.
"The Freedom Caucus will hurt the entire Republican agenda if they don't get on the team, & fast. We must fight them, & Dems, in 2018!" Trump tweeted.
Trump's characteristically strong-handed approach is another effort to bring the fiercely conservative group, which has repeatedly voted against Republican leaders in Congress, into line.
The Freedom Caucus has long been a thorn in the side of Republican leaders. But during eight years of a Democratic White House, their differences with mainstream Republicans were contained.
More From This Section
With Republicans now in charge of the White House, the House of Representatives and the Senate, those ideological differences have again come to the fore.
If they choose to, the Freedom Caucus could make Trump's life difficult in upcoming budget and tax debates.