WASHINGTON — President Trump convened his cabinet on Monday in the hopes of kick-starting his stalled domestic policy agenda and complained that Democrats in Congress are obstructing his efforts on tax reform, health care and the confirmation of judicial nominees.

“The Democrats have terrible policy,” Mr. Trump told reporters, flanked by Secretary of State Rex W. Tillerson and Jim Mattis, the secretary of defense. “They are very good at, really, obstruction.”

He also lashed out — without naming them — at “some Republicans” in the Senate, members he accused of refusing to go along with their party. He appeared to be talking about failed votes to repeal the Affordable Care Act.

“There are some Republicans, frankly, that should be ashamed of themselves,” Mr. Trump said, adding that most of the senators are “really, really great people” but saying that “you had a few people that really disappointed us.”