Robert Mueller’s investigation into alleged collusion and obstruction of justice is slogging toward a conclusion no one can yet predict.

The special counsel has conducted himself with consummate professionalism. The person he is investigating, Donald John Trump Sr., has not.

The president has been revealing for all the world to see the level of sleaze that has permeated his professional career. It has followed him into his private life. It well might have infected the presidency.

These audio recordings of Trump discussing payoffs of hush money to a Playboy model who alleges a nearly yearlong affair with the future president offer up only the latest case in point. The recordings come from Michael Cohen, who already has acknowledged paying another woman, porn queen Stormy Daniels, to keep her quiet about a sexual encounter she alleges having with Trump.

Trump denies both events occurred. Oh, but he paid these women the money. For what purpose? To buy them gifts? No. To keep them quiet!

Sleazy in the extreme.

It’s only the latest. The “Access Hollywood” recording of Trump bragging about he could grab women by their private area offers an even more graphic example.

The sleaze that surrounds the president has been built over many years. The very election of Donald Trump to the nation’s highest office does not erase it.

To think, too, that none of this was terribly surprising even during the 2016 presidential campaign. The 62 million Americans who cast their ballots for Trump more than likely knew at least tangentially about what he did during the entirety of his professional career. They knew about his serial philandering. They knew about how he has acted toward women and how he has lied at every turn.

Trump got their votes anyway.

It’s fair to ask: Has this level of sleaze become the new normal in American politics?

Sickening.