Mayor Bloomberg announced yesterday that the city would spend an additional $1.3 billion for school repairs and building projects, ending weeks of political combat over his prescription to pay for school construction.

The city had been counting on the $1.3 billion from Albany, but Governor Pataki didn’t include it in his budget, placing into doubt whether the public schools would receive money for much needed repairs and construction of new classrooms.

Mr. Bloomberg announced yesterday that he would bridge the gap by beefing up the city’s contribution this year.

“The total contribution that the city is making to the plan will not change,” Mr. Bloomberg said in a written statement. “We will double our commitment in the first year of the plan to $2.6 billion to make up for the state’s shortfall.”

The mayor’s decision does two things: It buys Mr. Pataki time to come up with the money he owes the city for schools and it robs Democratic challengers of a potent election-year issue. His critics can no longer say that the mayor cares more about a proposed stadium for Manhattan’s West Side than about building science labs and art rooms for city schoolchildren.

In his preliminary budget, Mr. Bloomberg didn’t use any city funds to make up for a shortfall in school construction spending from Albany, and critics said he was shortchanging city schools.

The speaker of the City Council, Gifford Miller, seized upon the issue and said just weeks ago that he would not allow the council to approve a budget if the mayor did not come up with the money that Albany refused to provide. Under Mr. Bloomberg’s compromise solution, the rejiggered spending formula will earmark $2.6 billion this year – the $1.3 billion it had planned to pay, plus the $1.3 billion it was expecting from Albany – for construction and reduce its spending on school projects over the next four years.

The mayor is counting on getting the money from the state by next year. His hope is that Albany will spend billions of dollars more on schools in the five boroughs as a result of a court order that says the state has not spent enough to give city students a “sound and basic education.” While Mr. Pataki has vowed to appeal the decision that grew out of lawsuit filed by the Campaign for Fiscal Equity, Mr. Bloomberg expects that the city will ultimately prevail.

“Albany’s failure to fulfill the obligations of the CFE lawsuit should not impact our school children,” Mr. Bloomberg said. “While the delays in capital work caused by the state’s failure to provide the capital money have been minimal up to now, our children deserve the best facilities we can possibly provide.”

Though Mr. Bloomberg’s move blunts attacks from his challengers, Mr. Miller and members of the City Council said the mayor’s decision was a victory. He buckled, they said, because of their pressure.

“I’m glad that he’s come around and I’m glad that he understood in the end what this means for children in real terms,” said Mr. Miller, one of four Democrats who wants to unseat Mr. Bloomberg. “And what does this mean? This means that 117,000 kids next year will get their toilets repaired, this means that 46,000 students in this city will get the science labs that they need … it means that 130,000 students will get the security and fire-alarm system upgrades that they need to keep them safe.”

The chairwoman of the council’s education committee, Eva Moskowitz, another critic of the mayor’s original spending plan, said that of her six years in office yesterday was “one of the happiest days of my life in government.”

“We fought for a large capital budget that would meet the needs of our children, and as soon as we got word that the administration was going to cut this budget, we got organized and drew a line in the sand,” she said.

For her part, the president of the United Federation of Teachers, Randi Weingarten, said the announcement was the “first good news for our schools – and our children – in quite a while.”

“I applaud the mayor for advancing city funds so that the schools’ capital infrastructure does not further deteriorate while we fight for the appropriate state share. And I applaud Speaker Miller for making the case so forcefully,” said Ms. Weingarten, whose union has been in a contract-negotiations deadlock with the mayor for months.

Where this might be less of a victory for Mr. Miller is in his freshly minted anti-stadium campaign that had relied on Mr. Bloomberg’s intransigence to build a groundswell of opposition to his plan to develop a West Side stadium.

On Monday, Mr. Miller launched a petition drive and Web site calling on the mayor to put school funding over the Sports and Convention Center that would include a stadium for the Jets and an expansion of the Javits Center.

The borough president of Manhattan, C. Virginia Fields, issued a statement called the measure a “stop gap” and saying the mayor needs to be more aggressive lobbying for funds in Albany. That is an issue all of his Democrat challengers have attacked him on.

And Fernando Ferrer, the Democratic frontrunner, called Mr. Bloomberg’s move “a good first step, but we could do even more to help our kids if the mayor would let go of his billion-dollar football stadium.”