President Donald Trump talked briefly with reporters Tuesday, expressing his regret that a “good man” like his former campaign manager Paul Manafort had been found guilty of eight counts of tax and bank fraud. The president quickly added that the case didn’t “involve” him and that it “had nothing to do with Russian collusion.”

He reportedly failed to address reporters’ questions about Michael Cohen, his former personal attorney and so-called “fixer,” who pleaded guilty Tuesday to breaking campaign-finance laws and other charges in a case that clearly did involve Trump.

Cohen admitted in court that he had made payments to two women to buy their silence about affairs they said they had with Trump, telling a U.S. district judge that the campaign-related fixing was “at the direction of the candidate” and “for the principal purpose of influencing the election for president in 2016.”

To amplify the point, the attorney who once said he would “take a bullet” for Trump alleged in court while under oath that his client, now the president of the United States, committed a felony.

The Manafort verdict was the first trial victory for special counsel Robert Mueller, while the Cohen plea agreement with federal prosecutors in New York may prove to be more damaging to Trump in the long run. The significance of both outcomes should be a wake-up call to Congress to reject any attempts to undermine Mueller’s ongoing investigation.

Among other things, the American people deserve to know if Mueller’s team found evidence supporting Cohen’s claims that Trump directed the payments in violation of campaign-finance laws. Americans also need clarity, once and for all, on whether the Trump campaign conspired with Russia to influence the election.

The investigation that Trump has repeatedly called a “witch hunt” keeps producing indictments and guilty pleas. On Monday, referring to Mueller’s probe, the president told Reuters that “I can go in, and I could do whatever — I could run it if I want.”

Indeed, many legal experts agree that Trump has the authority to orchestrate Mueller’s ouster. Congress, especially after Tuesday’s remarkable developments, simply cannot allow that to happen.