Well, this isn't very encouraging.

The Hill:

Comprehensive immigration reform legislation passed a significant hurdle Tuesday when the Senate voted overwhelmingly to begin consideration of the lightning-rod bill.

Thirty Republicans, including Senate Republican Leader Mitch McConnell (Ky.), voted to take up the measure in the 84-15 vote, revealing a deep well of potential support.

The vote tally was a promising sign of bipartisanship and the legislation appeared to have strong momentum after Speaker John Boehner (R-Ohio) predicted Tuesday that immigration reform would become law by year's end.

The bill will first have to emerge from the Senate, however, where many of the Republican "yes" votes on Tuesday warned they would not support the measure in a final vote unless its border security language was strengthened. 

It also remains unclear whether an immigration reform bill will emerge from the House, where there is strong opposition among conservatives to the Senate bill. 

Still, Boehner's comments highlight the pressure on the House - and on Republicans - to not be seen as obstacles to a bill despite opposition from grassroots conservatives. 

The GOP senators who voted "yes" on Tuesday included three of the four Republicans who helped draft the measure: Sens. Jeff Flake (Ariz.), Marco Rubio (Fla.) and Lindsey Graham (S.C.). Sen. John McCain (Ariz.) missed the vote.

The other GOP "yes" votes were McConnell and Sens. John Cornyn (Texas), Kelly Ayotte (N.H.), Deb Fischer (Neb.), Rob Portman (Ohio), John Thune (S.D.), Orrin Hatch (Utah), Jeff Chiesa (N.J.), Roger Wicker (Miss.), Pat Toomey (Pa.), Lamar Alexander (Tenn.), John Hoeven (N.D.), Richard Burr (N.C.), Rand Paul (Ky.), Susan Collins (Maine), Jerry Moran (Kan.), Roy Blunt (Mo.), Dan Coats (Ind.), Dean Heller (Nev.), Ron Johnson (Wis.), Bob Corker (Tenn.), Mike Johanns (Neb.), Johnny Isakson (Ga.), Tom Coburn (Okla.), Saxby Chambliss (Ga.), Lisa Murkowski (Alaska) and Chuck Grassley (Iowa).