The long-time Senator facing a primary challenge, a once-rare event that has grown increasingly common, spurs all sorts of reactions. Some rage against the activists. Some slip away from the party quietly. Perhaps the most common reaction is to desperately suck up to the base.

Jesse Zwick has a great (subscription-only, so subscribe!) report on the sad spectacle of Orrin Hatch, once the gold standard of GOP right-wingery, unsuccessfully trying to ingratiate himself with the handful of loons who control the state's party nominating process:

Due to Utah’s arcane nominating process, however, the real battle is fought at the grassroots level, and that’s where Hatch has encountered the stiffest resistance, although not for lack of trying. Utah’s primaries are largely decided by a mere 3,500 delegates who are elected at precinct meetings a few weeks before a state convention, meaning that Hatch has had to seek their votes by lavishing attention on the small group of very conservative activists who will decide his fate.
Kirkham, who owns a custom-made-auto company in Provo, says that the six-term senator has called him frequently, sometimes as often as three times a week, as well as on his birthday. Darcy Van Orden, a co-founder of the Davis County 9/12 Project and author of an unpublished manuscript titled The New Nazis, which describes how professors attempt to brainwash and indoctrinate students in the classroom, says she has also had her fair share of conversations with Hatch. 

The really sad thing is that they're not going to vote for him anyway. He'll lose his seat and his dignity.