Congress is in Washington this week, but will then be out of town for a two week Easter break, not returning until April 29.
At some point during that break, lawmakers expect to receive the redacted Mueller report from the Attorney General.
In his letter, Collins suggested hearing from Mueller in the days after Easter, even though the Congress would be on break that week.
"I think we can agree this business is too important to wait, and Members of the Committee will surely return to Washington at such a critical moment in our country's history," Collins wrote in his letter.
House Democrats quickly embraced the Collins' proposal, but said Mueller would testify after Attorney General Barr, as a May 2 hearing was set on the Mueller report by the House Judiciary Committee Chairman, Rep. Jerry Nadler (D-NY).