The Michigan Representative's comments on Saturday recommending Congress pursue obstruction of justice charges against Trump were the first instance of a sitting Republican in Congress calling for the President's impeachment, reports CNN.
Amash is a rare Republican critic of Trump and previously said the President's conduct in pressuring then-FBI Director James Comey could merit impeachment.
In a series of tweets on Saturday, Amash said he believed "few members of Congress even read" Special Counsel Robert Mueller's report and that the report itself established "multiple examples" of Trump committing obstruction of justice.
"Contrary to Barr's portrayal, Mueller's report reveals that President Trump engaged in specific actions and a pattern of behaviour that meet the threshold for impeachment," Amash tweeted.
Amash said he made his conclusions "only after having read Mueller's redacted report carefully and completely, having read or watched pertinent statements and testimony, and having discussed this matter with my staff, who thoroughly reviewed materials and provided me with further analysis".
He said Barr misled the public in a range of venues regarding the Mueller report, a charge Democrats and others have made repeatedly that the attorney general has disputed.
"Barr's misrepresentations are significant but often subtle, frequently taking the form of sleight-of-hand qualifications or logical fallacies, which he hopes people will not notice," Amash added.
While many Democrats have called for impeachment proceedings against Trump, many Republican members have agreed with the President's assertions about the Mueller report and defended his conduct, CNN reported.
Democratic Representative Rashida Tlaib, also of Michigan, responded to Amash's Twitter thread later Saturday and invited him to join her impeachment resolution.
".@justinamash come find me in 1628 Longworth. I've got an impeachment investigation resolution you're going to want to cosponsor," Tlaib tweeted.