Mr. Obama has said that in a private meeting with President Vladimir V. Putin of Russia last fall, he confronted Mr. Putin about the hacking, and told him “to cut it out, there were going to be serious consequences if he did not,” but that he had been reluctant to say anything publicly that would be perceived as affecting the presidential election.

Mr. Trump’s criticism of Mr. Obama for his handling of the Russian hacking, both in his recent tweets and in a TV interview over the weekend, seemed to be a tacit admission, for the first time, that Russia did attempt to undermine Hillary Clinton through hacking and the dissemination of fake news on social media.

But Monday brought caveats and counterattacks.

In an off-camera briefing for reporters, Sean Spicer, the White House press secretary, said only that Mr. Trump has long acknowledged that Russia “probably” tried to influence the election, adding that it was still possible that “other countries” were also involved.

Mr. Spicer demurred when asked to provide proof that anyone other than Russia attempted to sway the election. He also declined to say whether Mr. Trump accepted the finding that the Russians were not merely trying to meddle but were actively working on his behalf in an effort to defeat Mrs. Clinton.



A reporter read Mr. Trump’s comment made last July in which he said that he hoped Russian intelligence services had successfully hacked Mrs. Clinton’s email and encouraged them to publish whatever they may have stolen, and then the reporter asked Mr. Spicer how he could say the president took the threat of foreign meddling seriously.