"This is how we know we’re a real family here.”

KIEV, Ukraine — A month before Donald Trump clinched the Republican nomination, one of his closest allies in Congress — House Majority Leader Kevin McCarthy — made a politically explosive assertion in a private conversation on Capitol Hill with his fellow GOP leaders: that Trump could be the beneficiary of payments from Russian President Vladimir Putin.

“There’s two people I think Putin pays: Rohrabacher and Trump,” McCarthy (R-Calif.) said, according to a recording of the June 15, 2016, exchange, which was listened to and verified by The Washington Post. Rep. Dana Rohrabacher is a Californian Republican known in Congress as a fervent defender of Putin and Russia.

House Speaker Paul D. Ryan (R-Wis.) immediately interjected, stopping the conversation from further exploring McCarthy’s assertion, and swore the Republicans present to secrecy.

Before the conversation, McCarthy and Ryan had emerged from separate talks at the Capitol with Ukrainian Prime Minister Vladi­mir Groysman, who had described a Kremlin tactic of financing populist politicians to undercut Eastern European democratic institutions.

News had just broken the day before in The Washington Post that Russian government hackers had penetrated the computer network of the Democratic National Committee, prompting McCarthy to shift the conversation from Russian meddling in Europe to events closer to home.

Some of the lawmakers laughed at McCarthy’s comment. Then McCarthy quickly added: “Swear to God.”

Ryan instructed his Republican lieutenants to keep the conversation private, saying: “No leaks. . . . This is how we know we’re a real family here.”

The remarks remained secret for nearly a year.

The conversation provides a glimpse at the internal views of GOP leaders who now find themselves under mounting pressure over the conduct of President Trump. The exchange shows that the Republican leadership in the House privately discussed Russia’s involvement in the 2016 election and Trump’s relationship to Putin, but wanted to keep their concerns secret. It is difficult to tell from the recording the extent to which the remarks were meant to be taken literally.

The House leadership has so far stood by the White House as it has lurched from one crisis to another, much of the turmoil fueled by contacts between Trump or his associates with Russia.