In recent days, the scope and intent of Russia’s suspected involvement in the election has come into sharper focus. New disclosures by American officials now reveal that intelligence agencies concluded with “high confidence” that a desire to undermine American faith in the electoral system morphed into an effort to hurt Mrs. Clinton’s chances. One critical piece of evidence for this assessment was that suspected Russian hackers broke into the computer networks of both the Republican and Democratic national committees, but only leaked damaging emails from the latter.

At the urging of Democratic lawmakers, President Obama has asked the director of national intelligence to conduct a “full review” of Russia’s hidden hand in the election, the White House announced Friday. The inquiry, which is to be completed before Mr. Trump is sworn in on Jan. 20, is an important, if belated, step.

Weeks before the election, Mitch McConnell, the Senate majority leader, expressed skepticism about the intelligence reports and warned the White House that publicizing them would amount to a partisan act. The Republicans, however, did not protest when James Comey, the F.B.I. director, disclosed in a letter to Congress that a stash of emails found on Anthony Weiner’s computer appeared relevant to the investigation into Mrs. Clinton’s use of a private server. By the time Mr. Comey said there was nothing new, the innuendo bomb against Mrs. Clinton had exploded and the damage was done.

In a Fox News interview on Sunday, Mr. Trump dismissed the intelligence assessment about Russian meddling with contempt, and accused Democrats of “putting it out because they suffered one of the greatest defeats in the history of politics in this country.”

Some Republican lawmakers recognize the importance of standing up to Russia and taking steps to restore faith in the electoral system and institutions. A bipartisan group, led by Senator John McCain, a Republican, pledged Sunday to get to the bottom of Russia’s role, noting that the possibility that Moscow shaped the outcome of America’s election ought to alarm every American. “This cannot become a partisan issue,” said the statement, which was also supported by Senator Charles Schumer, the incoming leader of the Senate Democrats. Among the unanswered questions is whether anyone within Mr. Trump’s inner circle coordinated with the Kremlin and whether Moscow spread fake news to hurt Mrs. Clinton.