The group had run ads early on slamming Murphy as a "liberal" and criticizing some of his votes, but has been silent since — and with the primary just two weeks away, it's unlikely they'll get involved.
Former Capitol Hill staffer Evan Feinberg (R) showed some early promise, and secured the backing of his two former bosses, Sens. Tom Coburn (R-Okla.) and Rand Paul (R-Ky.). Both are popular with fiscal conservatives and Tea Party members. But Feinberg has struggled mightily to raise money — he'd raised less than $50,000 by the end of the year.
Murphy released a mid-February internal poll showing him with a 74 to 12 percent lead, and should be in a strong position for reelection. But he's not quite out of the woods: the Campaign for Primary Accountability, a deep-pocketed super-PAC targeting incumbents of both parties, is spending more than $200,000 in attempt to defeat him.
—This post was last updated at 6:02 p.m.