Runoff Elections for Mayor Likely to Be Moved to Oct. 1 The State Legislature appears poised to postpone the runoff election for the New York City mayoral primary by a week, adding yet another wrinkle to a wide-open campaign to succeed Michael R. Bloomberg. The Legislature is considering the new date as part of a bill to let the city's Board of Elections use its old lever voting machines in the primary and runoff instead of the electronic voting machines that were put in place in 2010. The Senate passed a bill allowing the changes last month, and the Assembly introduced a similar measure on Wednesday. With the primary set for Sept. 10, the new date of the runoff would be Oct. 1. The date of the general election is Nov. 5. City elections officials originally asked the Legislature to delay the runoff by one week as a part of a contingency plan for using the electronic machines. But a spokeswoman for the city's Board of Elections said that even if the lever machines were brought back, election officials still wanted three weeks to ensure they could determine the results of the primary and get ready for the runoff. "We believe we need three weeks, as it would give us the necessary time to pull off the runoff with less complications, especially in close contests," said the spokeswoman, Valerie Vazquez. Lawmakers also say that the current runoff date, Sept. 24, conflicts with the Jewish holiday of Sukkot. Postponing the runoff hinges on the Senate and the Assembly's reaching an agreement on the bill's language during the final days of the legislative session, which is scheduled to end on June 20, and the approval of Gov. Andrew M. Cuomo. Matt Wing, a spokesman for the governor, said Mr. Cuomo would review the legislation. Under New York State law, if no candidate in a primary for citywide office gets 40 percent of the vote, there is a runoff two weeks later between the top two candidates. At this stage of the mayoral campaign, most political analysts expect that the Democrats, with multiple major candidates, will have a runoff, and that the Republicans, with a smaller field, will not. Experts said that if, indeed, the Democrats had a runoff this year and the Republicans did not, delaying the runoff by a week would most likely benefit the Republican nominee, since it would give the Democrats less time - five weeks instead of six - to unite behind their nominee before the general election. "Reducing it to five weeks after a runoff makes it hard to patch up the hard feelings and put together the kind of coalition that you would want," said Kenneth Sherrill, an emeritus professor of political science at Hunter College. But the Democratic candidate could also wind up with more money than the Republican under the city's public matching funds program. The program allows participating candidates to spend $6.4 million on a primary and $6.4 million in the general election; candidates in a runoff can spend an additional $3.2 million for that campaign. All of the Democrats and all but one of the Republicans - the billionaire grocer John A. Catsimatidis - are expected to participate in the matching funds program. The mayoral candidates either declined to comment on the potential schedule change or said it was impossible to determine whom it would help. William C. Thompson Jr., a former comptroller and a Democratic candidate, said that he was "not a fan" of moving the runoff back, but that "I don't know that it helps or hurts anybody - you just don't know." Michael Morey, a spokesman for Christine C. Quinn, the City Council speaker and also a Democrat, said it was "impossible to say what the implications of a later runoff would be." Mr. Catsimatidis said: "I don't think a week is going to make a difference. What we want is accuracy and less stress for our workers. Three other candidates - Bill de Blasio, the public advocate and a Democrat; former Representative Anthony D. Weiner, also a Democrat; and Joseph J. Lhota, a Republican and former chairman of the Metropolitan Transportation Authority - declined to comment. Runoffs were introduced in New York City after the 1969 mayoral election, when the Democratic candidate, Mario A. Procaccino, was nominated in the primary with only 33 percent of the vote, and then defeated in the general election by the incumbent, John V. Lindsay, a Republican running on a third-party line. Since then there have been several runoffs in Democratic primaries for mayor, most recently in 2001, when then-Public Advocate Mark Green defeated Fernando Ferrer, the Bronx borough president, in a runoff, then went on to lose to Mr. Bloomberg in the general election. There has never been a runoff in a Republican mayoral primary.