It's important that everyone understand that Collins is not a real world moderate. The Rs are happy to let her vote against Trump when her vote doesn't matter, but when it does, like putting Kavanaugh on the SCOTUS, she's 100% Trump.
FWIW, this is the reason I'm adding the Maine Democratic Party instead:
Unlike the DNC, when Mills dropped out, they did the right thing by...
a) thanking her for her decades of service, and
b) remaining neutral until the primary was completed.