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 CoburnTom CoburnMcCain: No third-party foes coming for Trump Tough choice for vulnerable GOP senators: Embrace or reject Trump The Trail 2016: Donald and the Supremes MORE (R-Okla.) and Rand PaulRand PaulOvernight Energy: Trump outlines 'America First' energy plan in North Dakota Overnight Regulation: GOP slams new Obama education rules Paul blocks chemical safety bill in Senate MORE (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.