Regardless of the need for a solution to the illegal immigration problem (aside from simply enforcing current laws), passing a bill on immigration reform does the Republicans absolutely no good. Even if they authored the bill, and pushed it through the legislative process, Obama and the syncophants in the MSM will NOT give them any credit that they would be due. For an analogous example see the 1964 civil rights bill.
The Republicans will be adding millions of voters to the Democratic till, and for what? To be liked by the Washington elite? That's all they'll get out of it. That and no shot for the foreseeable future of holding the executive branch.
The welfare of humanity is always the alibi of tyrants