U.S. Sen. Susan Collins, R-Maine, has again warned President Trump not to interfere with Justice Department special counsel Robert Mueller’s ongoing probe of Russian involvement in the 2016 presidential election, including contacts and possible relationships with the Trump campaign.

“The president can’t set red lines for Bob Mueller,” Collins said in a joint CNN interview with Sen. Lisa Murkowski of Alaska, a fellow Republican moderate, that aired Friday morning.

“Well said,” Murkowski chimed in, endorsing Collins’ position.

Collins’ remarks, prerecorded Thursday afternoon, come a day after The Wall Street Journal and Reuters reported that Mueller has convened a grand jury and begun issuing subpoenas in Washington, D.C. Trump has said that any effort by Mueller to probe into his finances unrelated to Russia would be crossing a red line and would be “a violation.”

Collins and Maine’s junior senator, Angus King, who is an independent, both sit on the Senate Intelligence Committee, which is also investigating Russia’s involvement in the election.

Collins said Mueller’s issuing of subpoenas was a positive development and indicated that “the investigation is progressing to a new stage.”

“I think that’s good,” she told CNN’s Dana Bash. “The sooner that Bob Mueller and his team are able to get the facts out about Russian involvement and answer the question of whether or not there is any criminal wrongdoing or collusion between the Russians and members of President Trump’s campaign team, the better off we all are.”

She added that Mueller “should follow the leads wherever they may be” and that his investigation should not be “constrained beyond the mandate that he was given.”

Collins and King made similar statements July 21, shortly after the president had issued the warning about Mueller and his finances.

“It seems to me that the president – not to mention the country – would be best served by allowing this investigation to move forward unencumbered and to cooperate fully,” King said in a written statement at the time. Collins told reporters Trump would be making “an extraordinarily serious mistake” if he tried to fire Mueller.

In the CNN interview, Bash also asked Collins if Republicans were changing their stance toward the president. She said that many in her party were interested in his agenda, but not so tolerant of his style.

“I don’t think that the caucus is ignoring the president,” Collins said. “But there may be some ignoring of his rhetoric, which, at times, is over the top.”