Susan Collins is popular in Maine, she's GOP and she does as well with Ds and Is as GOP. GOP doesn't really like her in Maine, but she doesn't ever have a serious challenger in the primary or the general. Not a contested race.
Susan Colling is not running for re-election right now. Next is 2020. This Kavanaugh thing will be forgotten in 2020. In 2014, Collins won 68.5 to 31.5. 61 to 39 in 2008.