PORTLAND, Maine — Republican Sen. Susan Collins says President Donald Trump needs to stop publicly commenting on the investigation into coordination between the Russian government and his campaign.

Collins’ comments concerned Robert Mueller, who has been appointed as special counsel to investigate Russian election interference. Trump recently told the New York Times it would be a “violation” if Mueller looked at his personal finances as part of the probe.

Collins, a political moderate, says on CBS’s “Face the Nation” that it’s time for Trump to “step back and not comment.” She says Mueller is an “individual with the utmost integrity” and he must be allowed to complete his investigation.

Collins has challenged Trump and Senate Republicans a number of times. Recently, she has criticized efforts to repeal and replace the Affordable Care Act.