RLC is a 527 group that promotes libertarian principles in the Republican Party.

Here are some candidates they've already endorsed this time around:

Mark Bircher FL 13
Dan Bongino FL 19
Walter Jones (N.C.)
Justin Amash (Mich.)
Rebekah Johansen-Bydlak (Fla.)
Dr. Rex Rammell (Wyo.)
Rob Maness (La.)
Rand Paul (Ky.)

Here is their page for candidates to contact RLC to request endorsement:
http://rlc.org/candidates

They also have rated all Congress critters for their votes in 2015:
http://rlc.org/article/rlc-virginia-chairman-cliff-thies-releases-2015-libery-index