It was not clear what he meant to say, but the statement comes amid demands for Mueller to testify on Capitol Hill about his findings and tension with Attorney General William Barr over the handling of his report.
In his first public comments in the probe, Mueller said "it would be unfair" to potentially accuse someone of a crime when the person couldn't stand trial to defend himself.
And House Oversight Committee Chairman Elijah Cummings, D-Md., who previously said he could "foresee" impeachment proceedings against Trump, said Wednesday that Mueller's statement, "confirms both the evidence of obstruction by the president and the critical role of Congress under the Constitution going forward".
A senior White House official said "the White House was notified" on Tuesday night that Mueller might make a statement Wednesday.
Following Mueller's Wednesday remarks, Amash tweeted, "The ball is in our court, Congress."
For two years, Robert Mueller, the special counsel, led one of the most consequential investigations in the history of American politics - a pursuit that was the subject of endless speculation and cast an indelible cloud over Donald Trump's presidency.
Robert Mueller speaks for the first time on his Russian Federation investigation during a media briefing at the Department of Justice in Washington. "We did not however make a determination as to whether the president did commit a crime". "He did not use the word "impeachment" but said it was Congress" job to hold the president accountable for any wrongdoing.
Bruins rally past Blues in Stanley Cup Final opener
Add five penalties that gave the Bruins' playoff-leading power play too many chances, and the Blues have plenty to improve on. Depth can define a postseason, or at least chart its end course. "I thought they were the better team after that".
"A Special Counsel's Office is part of the Department of Justice, and by regulation, it was bound by that department policy", Mueller said, Speaking at the Justice Department in Washington DC.
A redacted version of the Mueller report was published in April, concluding there was no conspiracy between the Trump campaign and Moscow.
Calls to launch impeachment proceedings against Trump have grown among some Democrats, who have been frustrated by White House efforts to thwart congressional subpoenas seeking records and testimony related to the Russian Federation investigation and other matters related to Trump and his family.
"Bob Mueller clearly said, 'there was sufficient evidence.' He shredded the credibility of the attorney general, who mischaracterized the Mueller report and said that Mueller was not guided by Justice Department policy". The investigation ensnared dozens of people, including several top Trump advisers and a series of Russian nationals and companies.
Trump has blocked House committees' subpoenas and other efforts to dig into the Trump-Russia issue, insisting Mueller's report has settled everything.
In attacking Mueller's probe, Trump also has often attacked the integrity of the Federal Bureau of Investigation and its investigators.
Mueller's refusal to reach a conclusion on criminal obstruction opened the door for Barr to clear the president, who in turn has cited the attorney general's finding as proof of his innocence. "And that allegation deserves the attention of every American", Clinton said.