A fragile compromise that would legalize millions of unlawful immigrants risks coming unraveled after the Senate voted early Thursday to place a five-year limit on a program meant to provide U.S. employers with 200,000 temporary foreign workers annually. The 49-48 vote came two weeks after the Senate, also by a one-vote margin, rejected the same amendment by Sen. Byron Dorgan. The North Dakota Democrat says immigrants take many jobs Americans could fill. The reversal dismayed backers of the immigration bill, which is supported by President Bush but loathed by many conservatives. Business interests and their congressional allies were already angry that the temporary worker program had been cut in half from its original 400,000-person-a-year target. A five-year sunset, they said, could knock the legs from the precarious bipartisan coalition aligned with the White House. The Dorgan amendment "is a tremendous problem, but it's correctable," said Sen. Arlen Specter, R-Pa. The coalition will try as early as Thursday to persuade at least one senator to help reverse the outcome yet again, he said. Until the Dorgan vote was tallied, Specter and other leaders of the so-called "grand bargain" on immigration had enjoyed a fairly good day. They had turned back a bid to reduce the number of illegal immigrants who could gain lawful status. They also defeated an effort to postpone the bill's shift to an emphasis on education and skills among visa applicants as opposed to family connections. And they fended off an amendment, by Sen. Barack Obama, D-Ill., that would have ended a new point system for those seeking permanent resident "green cards" after five years rather than 14 years. All three amendments were seen as potentially fatal blows to the bill, which would tighten borders, hike penalties for those who hire illegals and give many of the country's estimated 12 million illegal immigrants a pathway to legal status.