WASHINGTON — President Obama has delayed action to reshape the nation’s immigration system without congressional approval until after the November elections, bowing to the concerns of Senate Democrats on the ballots, White House officials said on Saturday.

The decision is a striking reversal of Mr. Obama’s vow to take action on immigration soon after summer’s end. The president made that promise on June 30, standing in the Rose Garden, where he angrily denounced Republican obstruction and said he would use the power of his office to protect immigrant families from the threat of deportation.

“Because of the Republicans’ extreme politicization of this issue, the president believes it would be harmful to the policy itself and to the long-term prospects for comprehensive immigration reform to announce administrative action before the elections,” a White House official said. “Because he wants to do this in a way that’s sustainable, the president will take action on immigration before the end of the year.”

White House officials insist that Mr. Obama is more determined than ever to do that — eventually. But the president and his top aides have concluded that an immigration announcement before November could anger conservatives across the country, cripple Democratic efforts to retain control of the Senate, and severely set back any hope for progress on a permanent immigration overhaul.

White House aides began calling elected officials and immigration advocates Saturday morning to inform them that the president had decided not to act before the election. The president is expected to talk about the issue during an interview with NBC’s “Meet the Press” to be broadcast on Sunday.

The delay is certain to frustrate Hispanic activists who have been pressing Mr. Obama for months to sidestep Congress. Leaders of several immigration groups said their members would be furious with the president for raising — and then dashing — their hopes.

Mr. Obama’s advisers appear to have persuaded the president that he will be able to win back the support of immigrant activists, and create a personal legacy, if he waits until after the midterm elections to announce the sweeping executive actions.

The announcement’s timing has developed into a political problem for Mr. Obama. By saying that he would act on his own, the president heightened expectations among Hispanics that he would finally address the deportation fears of 11 million illegal immigrants, many of whom have been in the United States for decades.

Among the possibilities that administration officials have explored is the unilateral expansion of a program that would provide many illegal immigrants with work permits to allow them to legally live and work in the country indefinitely.

In June, Mr. Obama directed top officials to develop immigration options. “I expect their recommendations before the end of summer, and I intend to adopt those recommendations without further delay,” he said.

“Today,” he said, “I’m beginning a new effort to fix as much of our immigration system as I can on my own, without Congress.”

That pledge committed the president to acting in the weeks before the midterm elections, when a half-dozen Democratic senators must face the voters. Sensing a potentially powerful issue, Republicans have repeatedly accused Mr. Obama of preparing to usurp power from Congress and of wildly overstepping the authority of his office.

As the election draws closer, nervous Senate Democrats in Arkansas, Louisiana, North Carolina and Alaska have told White House officials that Mr. Obama’s actions could cost them victory at the polls. Those conversations culminated in the decision to delay immigration action.

-New York Times