OLD ORCHARD BEACH – Sen. Susan Collins had sharp criticism Thursday over President Trump's decision to fire Centers for Disease Control and Prevention director Susan Monarez.

“I am very concerned about and alarmed by this removal,” Collins said.

Trump fired Monarez yesterday.

Deputy White House Press Secretary Kush Desai told Spectrum News and the Associated Press that Monarez wasn’t “aligned with” Trump’s agenda. She was fired, he said, when she refused to resign.

Her attorneys say she refused to rubber-stamp unscientific directives and to fire health experts.

“I am extremely alarmed at the firing of the CDC director,” Collins told reporters following an appearance with the Maine Sheriffs Association. “I know her. I have met with her several times and talked with her on the phone, and I see no basis for her firing.”

Health and Human Services Secretary Robert F. Kennedy – whom Collins voted to confirm – said that the CDC has been "very troubled for a very long time."

"It's going to require getting rid of some people over the long term in order for us to change the institutional culture," Kennedy said on Thursday.

Collins noted that Monarez had only been in the position for three weeks. Four other top CDC officials also resigned this week, and Collins noted some of those officials had been with the department for “decades.”

Collins said those resignations coinciding with Monarez’s firing were “highly significant.”

Collins said she had spoken with her colleagues in the senate about the firing and learned that Trump did have the authority to fire Monarez. Still, she said several times that was “alarmed” by the firing.