
In the longest speech of his presidency, Mr Trump railed against the inquiry into alleged collusion between his campaign and Russia.
"We're waiting for a report by people who weren't elected," he told a crowd of cheering conservatives.
Mr Mueller is expected to hand in his report to the attorney general shortly. "Unfortunately, you put the wrong people in a couple of positions and they leave people for a long time that shouldn't be there and all of a sudden they are trying to take you out with bullshit, okay?" the president said.
Mr Trump has frequently called the special counsel's investigation a "witch hunt".