As of January 26, 2016: Rick Mulvaney [R-SC-5], Chris Stewart [R-UT-2], Thomas Massie [R-KY-4], John Ratcliffe [R-TX-4], Jim Jordan [R-OH-4], Steve Pearce [R-NM-2], Mark Walker [R-NC-6], Dave Brat [R-VA-7], Raul Labrador [R-ID-1], Rod Blum [R-IA-1], and Kevin Yoder [R-KS-3].
As of March 3, 2016: Rep. Barry Loudermilk [R-GA-11], Rep. Jim Bridenstine [R-OK-1], Rep. Tom Emmer [R-MN-6], and Rep. Doug Collins [R-GA-9]
Co-sponsors, there were nine in the House in the 112th Congress, when Rep. Marino (R-PA) was the sponsor.
We provide the first few words of the letter so that Congressional offices will see
the most important point right at the start, and so that no one can hijack our
system for another purpose. Here's the part we provide . . .
I want my representatives to co-sponsor Downsize DC's "One Subject at a Time Act" in the House (HR 4335) and the Senate (S. 1572).