Donald Trump Jr. (Stephanie Keith/Reuters)

FOR MONTHS, the Donald Trump campaign and then the Trump administration not only have cast doubt on the facts of Russian interference in the 2016 election but also have denied there was contact between Russian agents and Trump surrogates. We now know that this insistence was at best highly misleading. Top Trump officials met with a Kremlin-allied Russian lawyer in June 2016 — and they did so with the express hope of receiving compromising information about their Democratic rival. This represents a grave new set of facts in the ongoing investigation into possible Russian-Trump collusion.

The meeting, as first reported by the New York Times, took place after Mr. Trump had clinched the Republican presidential nomination but before the convention. Russian lawyer Natalia Veselnitskaya, who has campaigned against Western-imposed sanctions on Russia, met with Mr. Trump’s closest advisers: his eldest son, Donald Trump Jr.; his son-in-law, Jared Kushner; and the Trump campaign chairman at the time, Paul Manafort. The meeting was suggested, as The Post reported Monday, by a Russian pop star whose family has business ties both to the Russian government and to Mr. Trump.

For months, officials failed to disclose this meeting. When the record was corrected, they then mischaracterized its purpose. Mr. Trump Jr. and Reince Priebus, the White House chief of staff, passed it off as “a nothing meeting,” as Mr. Priebus said Sunday, that was “apparently about Russian adoption” — meaning about a controversy over whether foreigners could adopt Russian orphans. But hours later, after further reporting by the Times, the younger Mr. Trump admitted that he attended because he had been promised damaging material about the Hillary Clinton campaign. The Times further reported Monday night that he was informed that any such material “was part of a Russian government effort to aid his father’s candidacy.”

It will be up to federal prosecutors to determine whether federal conspiracy laws or election laws barring campaigns from soliciting help from foreigners have been implicated. What we already can say is that the plausibility of the Trump camp’s narrative, in which any underhanded Russian assistance came without the campaign’s witting participation, is eroding. The president’s associates must now explain interactions with Russians that they previously insisted never took place.

Mr. Trump Jr. claimed that he did not know the name of the person he would be meeting. His statement on the matter also indicated that, upon learning with whom he was meeting, he ended the encounter after it “became clear that she had no meaningful information.” If he had the proper concern about foreign influence on the election system, not to mention election law, he would have immediately ended any meeting premised on the offer of campaign help when learning the other party was a Russian national.

The latest revelations only intensify the questions surrounding Mr. Trump’s firing of FBI Director James B. Comey after Mr. Comey, according to his own testimony, declined to pledge personal loyalty to the president. They also intensify the urgency of a careful Senate vetting of Mr. Trump’s nominee to replace Mr. Comey, Christopher Wray, who will testify before the Senate Judiciary Committee on Wednesday. Mr. Wray must commit to the independence of the FBI by detailing any conversations he had with Mr. Trump, and in particular whether the president asked him for his loyalty. He must be able to say that he made no such commitment. And he must promise that he will do everything to cooperate with, and nothing to impede, the special counsel’s Russia investigation.