UPDATED

By Lauren Camera and Alyson Klein

House leaders may hold off until next week on a final vote on a Republican-backed bill to rewrite the No Child Left Behind law, amid pushback from powerful GOP lobbying groups who may have succeeded in convincing enough Republicans that the measure is not conservative enough, according to several sources. UPDATE (3:23): The bill has been officially postponed, according to House leaders.

Part of the problem: House GOP conservatives are unhappy with their leadership’s handling of a bill that would temporarily continue funding for the Department of Homeland Security, which administers a controversial immigration program created through executive authority by the Obama administration.

House leaders had initially hoped to have the bill over and done with Friday. But a morning notice from Majority Whip Steve Scalise, R-La., who keeps track of how many members of his party support measures as they come to the floor, did not specify a final vote for the bill, which he normally would have if it were to occur during a series of votes scheduled for later this morning.

And while Republicans have the procedural ability to vote on bill as soon as amendment debate is over, the notice from Scalise did not specify that.

[UPDATE (3:00 p.m.): Congressional leaders put the delay on the need to pass a homeland security funding bill first, an assertion Rep. John Kline, R-Minn., the chairman of the House education committee, repeated in an interview Friday.

But, when pressed on whether or not Republican leaders had sufficient support for the bill, he said, “I don’t know...I know it is close. I hope we have enough votes to go forward.”

In 2013, Kline was willing to jettison a personal priority—a requirement for districts to tie teacher evaluation in part to test scores—in order to gain support for a very similar NCLB rewrite bill. Would he be willing to make changes to this version of the legislation?

“I am not conceding that anything needs to change,” Kline said. He added that he was still hoping the House could stick to its original plan of passing the bill Friday.

But a congressional aide with knowledge of the proceedings said, for now, the final vote on the NCLB rewrite appeared likely to be bumped to next week. At that point, Republican leaders will probably be able to muster the neccesary votes to get the bill through the chamber, sources say. But if not, the bid to update the NCLB law this year could be in serious trouble.]

Ahead of the Thursday debate, the Club for Growth and Heritage Action, two powerful conservative lobby organizations, blasted out emails to House Republicans in opposition to the bill. They warned that if members voted in favor of the measure, it would count against them in a scoring rubric the organizations use to rate which members are most faithful to conservative principles and the GOP Party. The groups’ problem with the NCLB overhaul? It’s not conservative enough.

Among other things, the groups wanted to see legislation that knocks the federal government entirely out of education, which they view as strictly a state and local responsibility. They also hoped to see provisions in the bill that would have allowed federal funds for low-income students to be used at private schools.

Part of the problem here is timing, sources say. Conservative Republicans are angry at House leaderships’s handling of immigration legislation—and they are taking their frustration out on what some see as a relatively moderate education bill.

During floor debate, Rep. Todd Rokita, R-Ind., who heads up the subcommittee on K-12 policy and is also an author of the bill, told his fellow Republican lawmakers that was a good alternative to NCLB as it stands. “Everything in the [Republican bill] is better than current law,” he said.

UPDATE: The delay is not official yet, but Rep. Justin Amash, R-Mich., a teaparty superhero, tweeted that the bill has been yanked. And he sounds pretty happy about it.

Great news: Reauthorization of #NoChildLeftBehind (#HR5) has been pulled from consideration. Your calls, emails & tweets made a difference!

— Justin Amash (@repjustinamash) February 27, 2015