The bill passed the House on Thursday with the support of 87 Republicans, while 138 voted against it.
Some other potential GOP Senate candidates did vote for it, however: Reps. Charles Boustany (La.), Erik Paulsen (Minn.), Patrick McHenry (N.C.) and Shelley Moore Capito (W.Va.) supported the bill.
The high number of potential Senate candidates voting against the bill stands in contrast to the voting pattern of potentially vulnerable House Republicans, most of whom voted for the bill.
Sixteen Republicans who Democrats hope to target backed the bill: Reps. Lou Barletta (Pa.), Dan Benishek (Mich.), Jim Gerlach (Pa.), Chris Gibson (N.Y.), Michael Grimm (N.Y.), Richard Hanna (N.Y.), Scott Rigell (Va.), Chris Collins (N.Y.), Rodney Davis (Ill.), Jeff Denham (Calif.), Tom Latham (Iowa), David Joyce (Ohio), Sean Duffy (Wis.), Mike Fitzpatrick (Pa.), David Valadao (Calif.) and Jackie Walorski (Ind.).
Potentially vulnerable Republicans who voted against it include Reps. Kerry Bentivolio (Mich.), Reid Ribble (Wis.) and Frank Wolf (Va.), though all three appear fairly secure in their reelection bids early on.
This post was updated at 5:10 p.m.