As President Trump makes an abrupt pivot toward Russia, upending generations of American foreign policy, he is also defying members of his own party in Congress, many of whom have spent their careers arguing for a hawkish stance against Moscow and strong backing for allies in Europe facing its most immediate threats.
But the response from Republicans on Capitol Hill has been muted, in some cases to the point of silence. There has been little G.O.P. pushback on Mr. Trump’s efforts to draw closer to President Vladimir V. Putin of Russia or blame Ukraine as he seeks to bring a quick end to the war that began when Russia invaded the country.
While some Republicans have expressed dismay at Mr. Trump’s moves and statements, there has been no concerted effort to challenge him from G.O.P. leaders or senators who play pivotal roles in overseeing military and foreign policy in Congress.
“Right now, you have got to give him some space,” Senator John Thune, the South Dakota Republican and majority leader, said at a news conference on Capitol Hill Wednesday after a closed-door Senate lunch with Vice President JD Vance.
The weekly meeting often provides senators an opportunity to iron out internal disputes. A few senators expressed a desire to use at least part of the time to press Mr. Vance about Mr. Trump’s apparent willingness to abandon American allies, draw nearer to Mr. Putin and denounce President Volodymyr Zelensky of Ukraine as a “dictator.”
But when the time came, the topic did not come up, according to several attendees.
“What I’m in support of is a peaceful outcome and result in Ukraine,” Mr. Thune told reporters after the meeting, “and I think right now the administration, the president and his team are working to achieve that.” Of Mr. Trump’s labeling of Mr. Zelensky as a dictator, he said only: “The president speaks for himself.”