This happened earlier this week:

A former top aide to former Sen. Olympia Snowe (R-Maine) said in an op-ed published on Sunday that she would not back Sen. Susan Collins’s (R-Maine) reelection bid, arguing that the longtime incumbent has proven unwilling to break ranks with her party and President Trump.

“Sadly, I can no longer support Senator Susan Collins,” Jane Calderwood, who served under Snowe in both the House and the Senate for nearly two decades, wrote in an op-ed published by SeacoastOnline.com.

“She has proven unwilling to stand up to the President and too enamored of political power to speak up for the good people of Maine,” Calderwood added. “I am tired of hearing about how ‘concerned’ she is. These times demand strength and action and she has shown neither.”