Under pressure from Mr. Trump and his Republican allies in Congress, the Justice Department said in March that it would begin an investigation into the surveillance of Mr. Page. Law enforcement officials had long had concerns that Mr. Page, a former investment banker based in Moscow, was acting as a Russian agent.
But the president has continued to make the allegation that the court-ordered surveillance of Mr. Page was unjustified. Mr. Trump has also continued to claim that the special counsel should be looking not at his campaign, but instead at his 2016 rival, Hillary Clinton.
â€śAt what point does this soon to be $20,000,000 Witch Hunt, composed of 13 Angry and Heavily Conflicted Democrats and two people who have worked for Obama for 8 years, STOP!â€ť Mr. Trump wrote in a pair of tweets. â€śThey have found no Collussion with Russia, No Obstruction, but they arenâ€™t looking at the corruption in the Hillary Clinton Campaign where she deleted 33,000 Emails, got $145,000,000 while Secretary of State, paid McCabes wife $700,000 (and got off the FBI hook along with Terry M) and so much more.â€ť
It was not clear where Mr. Trumpâ€™s estimate of the cost of Mr. Muellerâ€™s inquiry came from. The Justice Department reported at the end of last year that the special counselâ€™s investigation had incurred at least $6.7 million in expenses in its first four and a half months, and Mr. Trumpâ€™s own budget allocated $10 million for his office for 2019.
The president has often charged that Mr. Mueller is leading a team of Democratic activists who are out to get him, citing reports that some of his investigators are Democrats who supported Mrs. Clinton. He has also sought to discredit Andrew G. McCabe, the former deputy F.B.I. director, by noting that his wife ran as a Democrat for political office in Virginia with support and campaign donations from Terry McAuliffe, a close Clinton ally.
But Mr. Mueller himself is a Republican, as are several members of his staff, and the investigation is being overseen by Mr. Rosenstein, another Republican, who was Mr. Trumpâ€™s own choice to be deputy attorney general.
That did not stop the president from suggesting that the investigation was politically driven and should end.
â€śRepublicans and real Americans should start getting tough on this Scam,â€ť he tweeted on Sunday.