WASHINGTON — It became such a central slogan of Donald J. Trump’s 2016 campaign that at rallies his supporters would chant the three words representing his pledge to take on big donors and special interests: “Drain the swamp.”

But as President Trump ramps up his 2020 re-election bid, it is clear that he has tolerated if not fostered a swamp of his own in Washington, granting up-close access to deep-pocketed supporters and interest groups willing to write six- and seven-figure checks to his political operation. Some have used the opportunity to plead their cases directly to him.

The latest evidence came over the weekend, with the release of a secret recording of an April 2018 dinner for major donors and prospective donors to a super PAC supporting Mr. Trump.

While news of the recording primarily focused on Mr. Trump’s call for the removal of Marie L. Yovanovitch as ambassador to Ukraine after a donor claimed she had disparaged the president, the recording revealed that Mr. Trump engaged in policy discussions with many other donors pushing their own agendas.