President Bush is appealing to conservative Republicans not to block reauthorization of landmark education reform that is central to his domestic legacy.

Bush also offered a warning to congressional Democrats whom conservatives suspect will seize upon the expiration of the No Child Left Behind Act to expand federal spending on education significantly.

Speaking in New York on Wednesday, the president called on Congress to reauthorize the No Child Left Behind Act, which became one of the first big achievements of his administration.

“My call to the Congress is, don’t water down this good law,” Bush said. “Don’t go backwards when it comes to educational excellence. Don’t roll back accountability. We’ve come too far to turn back. So Congress needs to work with this administration to pass legislation that helps — gives our children the education they deserve.”

But he faces opposition from conservatives, including leaders of his own party.

Republican Sens. Tom Coburn (Okla.); John Cornyn (Texas), vice chairman of the Senate Republican Conference; Chuck Grassley (Iowa), ranking Republican on the Finance Committee; Jon Kyl (Ariz.), chairman of the Senate Republican Conference; and Mel Martinez (Fla.), chairman of the Republican National Committee, have joined South Carolina Sen. Jim DeMint (R) to sponsor legislation that would overhaul Bush’s cherished education law.

Rep. Pete Hoekstra (R-Mich.) has introduced a companion bill in the House.

No Child Left Behind officially expires on Sunday, but will receive an automatic one-year extension.

Senate conservatives have offered instead the A-Plus Act, which would overhaul No Child Left Behind. It would enable states to accept federal education money without having to accept national curricula and testing methods. It would allow states to opt out of the federal regimen if they agree to certain performance criteria.

Bush aides believe Senate conservatives’ proposal would gut No Child Left Behind, according to Republican sources.

“I know how strongly they feel about the existing law,” said Mike Franc, vice president for government relations at the Heritage Foundation, a conservative think tank. “The premise of A-Plus is that No Child Left Behind has to be dramatically overhauled, and that’s fundamentally contrary to the president.”

Conservative sponsors of A-Plus say its provisions were once a part of No Child Left Behind but were removed to reach a compromise with Democrats.

Franc is one of many conservatives who dislike much about No Child Left Behind. He says it does not sufficiently strengthen parents’ school choice to justify a broad expansion of federal law.

The House Education and Labor Committee has held nearly two dozen hearings on reauthorization. Chairman George Miller (D-Calif.) is expected to introduce reauthorization legislation in the next two weeks, a House aide said.

In the Senate, Edward Kennedy (D-Mass.), chairman of the Senate Health, Education, Labor and Pensions Committee, is expected to move a reauthorization bill in early October, said a Senate aide.

DeMint told The Hill that he will try to block reauthorization unless No Child Left Behind is overhauled to satisfy conservatives’ concerns, which the president does not share.

“The country would be better off if we didn’t reauthorize it and just continue the status quo, rather than expand it, which is what’s going to happen,” said DeMint, voicing a suspicion that congressional Democrats will take the opportunity to expand vastly the federal government’s role in education. “If Republicans don’t unite behind an idea that’s better, the Democrats are going to push through federalization of schools,” he said.

It would be almost impossible for the Democratic-controlled Congress to pass legislation palatable to fiscal conservatives, DeMint added. “With a Democratic majority it’s going to be harder to get anything through that’s not a lot more spending and a lot more federal control. I don’t hold out a lot of hope.”

Coburn said he would also oppose reauthorization unless it includes major reforms. “Unless they markedly change No Child Left Behind, I won’t support it,” he said.

Grover Norquist, who as president of Americans for Tax Reform holds regular meetings with conservative leaders, said many dislike Bush’s landmark education law.

“I don’t know any conservative leader who is happy with it,” said Norquist. “I know a bunch who are very unhappy about it. There is an automatic view — ‘the federal government is involved in education’ and ‘what’s the federal government doing in education?’”

Norquist said many conservatives on principle oppose any law that allows Washington to direct state and local education.

Conservative opposition has spurred several Republicans who first supported No Child Left Behind to change their minds.

“I guess it deals mostly with the feeling that No Child Left Behind, even though I voted for it, probably went further in national policy than it should,” said Grassley when asked why he is taking a position that Bush opposes. “Basically, what we’re trying to do is give more flexibility to the states.”

While Bush must contend with conservatives who want to restructure his education reform program, he must also beat back Democrats who want to pour billions more dollars into it.

“Today President Bush called on Congress to reauthorize the No Child Left Behind Act and not to turn back the clock on educational excellence,” said Kennedy in a statement Wednesday. “Unfortunately, this administration has dropped the ball on education reform by shortchanging this law to the tune of $56 billion since its enactment.”