By ERICA WERNERWASHINGTON (AP) â¿¿ High-tech companies looking to bring more skilled workers to the U.S. pushed Monday for more concessions in an immigration bill pending in the Senate. Labor unions said the Silicon Valley had already gotten enough in the legislation and further changes risked chipping away at protections for U.S. workers. The clash is set to play out in a Capitol Hill hearing room this week as the Senate Judiciary Committee resumes consideration of amendments to sweeping legislation remaking the nation's immigration system. At issue are the highly sought-after H-1B visas that allow companies like Google and Microsoft to bring workers to the U.S. to fill job openings for engineers, computer software experts, and other positions where employers say there's a shortage of U.S. workers. The legislation increases the number of these visas that are available, but also adds in a number of restrictions designed to ensure U.S. workers get a first shot at jobs. Those protections were championed by Sen. Dick Durbin, D-Ill., a Judiciary Committee member who's also part of the bipartisan "Gang of Eight" senators who authored the immigration legislation. But high-tech companies have their own champion on the Judiciary Committee: Republican Sen. Orrin Hatch of Utah, who's prepared a slew of amendments to help their cause. Hatch is seen as a potential swing vote on the immigration bill so backers of the legislation, who are working assiduously to ensure their bill passes the Senate with as many votes as possible, would like to court his support. But Durbin opposes Hatch's efforts and he and other Democrats are under pressure from organized labor not to go along. "We deemed the current language in the bill to be the compromise. After all, high tech got an awful lot of what it wanted, including the visa limit going up nearly threefold," said Tom Snyder, immigration campaign manager for the AFL-CIO. "Now they want to compromise the compromise."