She is afraid of the money pledged to her opponent if she votes YES. Collins believes the folks with the money won't spend it on her opponent.
Republicans shouldn't be this stupid.
She should be more afraid of running against that money after Mitch strips her of any influence, pork, and her committee assignments...
It's easier if you look important to the electorate.
...but that also assumes Mitch would have the balls to do that.
It should be made clear to Collins if she votes no, there will be no money from the RNC or the Senate campaign fund. In addition, the money will go to whoever challenges her in the primaries.