She says while she would love being in ME full-time where most of her family and friends are, she can do the most good for Mainers and the nation by staying in the U.S. Senate. But Maine constitutional law expert Marshall Tinkle said she wouldn't have to resign to run and could pick her successor after being sworn in.
Even Collins' family members, many of whom still live in her hometown of Caribou, said they've been left in the dark regarding her decision.
"In the Senate, I now have significant seniority, and that allows me to do a lot", she told Maine's WGAN radio at the time. While many people feel that she would easily win a general election, there are substantial questions regarding her ability to survive a crowded Republican primary.
Susan Collins to run for ME governor.
"This decision has not been any easy one".
"I am a congenital optimist, and I continue to believe that Congress can - and will - be more productive", she said. She would have been the clear front-runner in a governor's race now filled with lesser known candidates.
In a Senate where Republicans hold a slim 52-48 majority and Democrats are broadly united against much of Trump's agenda, Collins's vote can be pivotal.
But a gubernatorial bid by Collins would also have been risky - the biggest threat coming from within her own party.
She would have joined a crowded field in the race for governor to replace two-term Republican Gov. Paul LePage, who can not run again because of term limits, and her decision will likely free more gubernatorial candidates who have been waiting on the sidelines to enter the race.
The governor has since used his weekly radio addresses and conservative radio appearances to berate Collins over her opposition to two controversial bills repealing the Affordable Care Act. Since Mr. Trump became president, she has voted less often with her party than any other Republican senator.