He joins House Majority Whip Kevin McCarthy (R-Calif.), former Florida Gov. Jeb Bush (R) and Sen. Mike Lee (R-Utah), a Tea Party favorite, in recent Romney endorsements.
There is a push by some in the GOP to rally around Romney and end the primary soon so as to avoid additional intra-party bloodletting. Other conservative Republicans who've praised Romney in recent days include Sens. Pat Toomey (R-Pa.) and Jim DeMint (R-S.C.).
This post was updated at 11:30 a.m.