When President Bush and Democratic leaders put together the bipartisan coalition behind the federal No Child Left Behind Act, they managed to override or flat out ignore decades of sentiment that education is fundamentally a prerogative of state and local government.Now, as the president and the same Democrats push to renew the law, which has reshaped the face of American education with its mandates for annual testing, discontent with it in many states is threatening to undermine the effort in both parties.Arizona and Virginia are battling the federal government over rules for testing children with limited English. Utah is fighting over whether rural teachers there pass muster under the law. And Connecticut is two years into a lawsuit arguing that No Child Left Behind has failed to provide states federal financing to meet its requirements.Reacting to such disputes, dozens of Republicans in Congress are sponsoring legislation that would water down the law by allowing states to opt out of its testing requirements yet still receive federal money.On the other side of the political spectrum, ten Democratic senators signed a letter last month saying that based on feedback from constituents, they consider the law's testing mandates to be ‘‘unsustainable’’ and want an overhaul.‘‘It’s going to be a brawl,’’ said Jack Jennings, a Democrat who as president of the Center on Education Policy has studied how the law has been set up in the 50 states. ‘‘The law is drawing opposition from the right because they are opposed to federal interference and from the left because of too much testing.’’The law was passed in Bush’s first year in office by large bipartisan majorities — 87 to 10 in the Senate and 381 to 41 in the House. Today it enjoys the support of a powerful, if unlikely, political threesome — Bush and the Democratic leaders of the education committees, Senator Edward M. Kennedy of Massachusetts and Representative George Miller of California. But many members of Congress have heard years of complaints about the law from educators and parents in their states, and even lawmakers who support its goals believe that it is headed for a makeover, or that its revision could be postponed until after the 2008 election. No Child Left Behind greatly expanded the federal role in education with hundreds of directives. It requires states to test students in elementary and middle school every year and bring them to proficiency in reading and math by 2014. It also imposes sanctions on schools where scores consistently fall short of achievement targets.Foes and supporters of the law dispute whether the federal government’s role should be more robust or diminished. There are also disputes over how much money should go to education, how to create an accountability system that accurately identifies failing schools and whether to soften the 2014 deadline.A private bipartisan commission on No Child Left Behind has called for significant strengthening of the federal role, including requiring all states to build a statewide computer system capable of tracking every student’s academic performance, at a cost of billions. ‘‘The theme to the commission’s proposals is ‘Do more, and do what Uncle Sam tells you to do,’’’ two former Education Department officials, Chester E. Finn Jr. and Michael J. Petrilli, wrote recently. Finn served under President Ronald Reagan, and Petrilli under Bush.In contrast, a bill sponsored by Representative Peter Hoekstra, Republican of Michigan, and co-sponsored by 50 conservative Republicans in the House, including the minority whip, Roy Blunt of Missouri, would greatly weaken Washington’s control by allowing states to opt out of the law’s testing requirements without losing federal money. Two Republican senators, Jim DeMint of South Carolina and John Cornyn of Texas, have introduced companion legislation in the Senate.Whether the law can emerge strengthened or survive in any recognisable form depends on the alliance of Bush, Kennedy and Miller. The two Democrats have fought Bush over the Iraq war, tax cuts and other policies. But as the ranking Democrats on the education committees in 2001, they helped forge the law, negotiating big increases in education financing. They have since accused the Republicans of providing less money than promised. Still, in an interview, Miller expressed impatience with lawmakers who, he said, failed to understand the law’s strategic importance to the nation’s future. ‘‘You can get into a lot of petty politics, but there’s a mandate coming from across the country for us to improve this law,’’ he said. Among Republicans, Education Secretary Margaret Spellings is working to minimise defections. This week, she has been stumping for the law in Arizona where all four House Republicans have signed on to Hoekstra’s bill. Spellings’s press secretary, Katherine McLane, said: “We’re optimistic about getting NCLB reauthorised this year.” Still, many state, suburban and rural district superintendents dislike the law, and their views are influential with Congressional delegations. Tom Horne, a Republican who is Arizona’s superintendent of public instruction, has feuded with Spellings over a ruling that gives the state’s schools one year to teach immigrant students English before schools are accountable for their scores on exams, which under Arizona law must be given in English. But Horne said the department should make an allowance for Arizona, facing an endless flow of new immigrants. ‘‘You cannot run a complex, continentwide education system through micromanagement by people living in an ivory tower at the Department of Education in Washington,’’ Horne said. Utah has rankled under the law’s requirement that educators have the equivalent of a college degree in every subject they teach. Few teachers want to serve in Utah’s remote towns, where authorities often ask a teacher with a math degree to pitch in and teach, say, geography. ‘‘That’s how rural America works, and Washington doesn’t get it,’’ said Patti Harrington, the state superintendent of public instruction. Representative Rob Bishop, who represents Utah’s rural western half, said he shared her view.-SAM DILLON