Union of federal workers opposes immigration bill WASHINGTON - Senators pushed forward Monday with changes to a sweeping immigration overhaul over the objections of a union of immigration officers that announced its opposition to the bill. The legislation, written by a bipartisan group of senators, has largely withstood challenges and is on track for a key vote this week as the Senate Judiciary Committee prepares to pass the measure to the full chamber. As the committee convened for its fourth day of hearings, the National Citizenship and Immigration Services Council, which represents about 12,000 employees at U.S. Citizenship and Immigration Services, announced its opposition, saying provisions in the bill could lead to fraud. Kenneth Palinkas, the council's president, said the legislation would "damage public safety and national security and should be opposed by lawmakers." The union's decision gives a boost to the bill's opponents. The immigration officers union joins the National ICE Council, which had previously announced its opposition. That union represents about 8,000 deportation officers and other staff at U.S. Immigration and Customs Enforcement. At the same time, a key Republican, Sen. Orrin G. Hatch of Utah, said he would be inclined to vote for the bill in committee if agreement could be reached on his proposals to expand the visa program for high-skilled workers. Much of the day's action was pushed behind the scenes as talks continued on Hatch's amendments, which are important to big business and the technology sector because they would loosen rules for hiring more foreign workers. Organized labor opposes Hatch's approach, saying it would take jobs from U.S. citizens. The bill involves intricate political and policy trade-offs. It would increase border security, start a new low-skilled guest-worker program and require all employers to verify the legal status of their workers. In exchange, the estimated 11 million immigrants who entered the country illegally or overstayed visas would be offered a 13-year path to citizenship, after they paid fines and taxes and learned English. So far, senators have dispatched more than 100 amendments. They have turned back those that would derail the bipartisan compromise, while accepting others that could potentially broaden support. One area of continued concern among senators has been how to stop immigrants from staying in the country after their visas expire - a central problem because nearly half the immigrants in the country without proper status entered legally but overstayed visas. Many senators have said they want an exit visa system that relies on biometric controls, such as fingerprints, to screen immigrants as they leave the country. But they have rejected amendments to mandate such a system as too cumbersome and costly, particularly for airlines. On Monday, the senators approved a compromise: A biometric exit visa system would be required at 10 of the nation's 30 busiest international airports within two years after the bill became law and at the other 20 airports within six years. Supporters called it a good first step despite objections from opponents, including Sen. Jeff Sessions (R-Ala.), who pushed for a mandatory system. Sessions has led Republican opposition to what started out as an 844-page bill. He offered several amendments that were voted down Monday, including one that would reject immigrants applying for legal status if they have used food stamps or Medicaid healthcare. Several amendments, offered by Republicans and Democrats, were accepted. One would prevent children and mentally ill immigrants from being held in solitary confinement if they were arrested for immigration law violations. Another would ensure penalties for attempted passport fraud. The 18-member Senate Judiciary Committee is expected to approve the bill as soon as Wednesday with support from most of the Democrats and at least the two Republicans who were part of the group that drafted the legislation. The full Senate would take up the bill once Congress returned from its break, in early June.