Sen. Jim DeMint at Immigration Reform Press Conference, originally uploaded by Rob Bluey.

Last night’s defeat of the immigration bill came after three weeks of intense grassroots activism against the legislation. But this bill may not have gone up in flames had it not been for the craftiness of four Republican senators who voted with Democrat Sen. Byron Dorgan to sunset the temporary-worker program after five years.

The “poison pill” amendment was considered a deal-breaker by supporters of the bill. Having failed by just one vote on May 24, it came up again Wednesday; only this time, four Republicans who had previously opposed it voted the opposite way. As the Washington Post notes this morning, they realized that siding with Democrats was the only way to kill the legislation.

So who are these Republicans? Senators Jim Bunning (Ky.), John Cornyn (Tex.), Jim DeMint (S.C.), Elizabeth Dole (N.C.) and Mike Enzi (Wyo.) took a stand against the immigration bill and faced tremendous pressure for doing so. They held firm, however, and deserve credit for using a crafty strategy to sink the legislation.