Roman Catholic and Orthodox Jewish officials in New York are mounting an intense lobbying effort to block a bill before the State Legislature that would temporarily lift the statute of limitations for lawsuits alleging the sexual abuse of children.

A perennial proposal that has been quashed in past years by Republicans who controlled the State Senate, the bill is now widely supported by the new Democratic majority in that chamber, and for the first time is given a good chance of passing.

If signed by Gov. David A. Paterson, a longtime supporter, the bill would at minimum revive hundreds of claims filed in recent years against Catholic priests and dioceses in New York, but dismissed because they were made after the current time limit, which is five years after the accuser turns 18. Similar legislation has passed in Delaware and in California, where a 2003 law led to claims that have cost the church an estimated $800 million to $1 billion in damages and settlements.

The rekindled prospects of the New York bill, known as the Child Victims Act, come at a delicate juncture for the Archdiocese of New York, the nation’s flagship see, where Cardinal Edward M. Egan is scheduled to hand over the reins in April. His successor, Archbishop Timothy M. Dolan of Milwaukee, was so hard hit by settlements for past abuse by priests in that archdiocese that he was forced to put its headquarters up for sale.

“We believe this bill is designed to bankrupt the Catholic Church,” said Dennis Poust, spokesman for the New York State Catholic Conference, a group representing the bishops of the state’s eight dioceses. He said that Cardinal Egan and Bishop Nicholas A. DiMarzio of Brooklyn visited Albany this week to voice their opposition, and that a statewide network of Catholic parishioners had bombarded lawmakers via e-mail.

But while the Catholic Church is leading the opposition, in recent months a loose coalition of disparate groups has also joined the effort. They include leaders of the Hasidic and Sephardic Jewish institutions in Brooklyn, which could face equally costly abuse claims. The New York criminal defense bar oppose lifting statutes of limitation as unfair to the accused, who must defend themselves against claims of transgressions decades old.

Under the Albany measure, which Assemblywoman Margaret M. Markey, a Queens Democrat, has shepherded to Assembly approval in each of the last three sessions, people claiming they were sexually abused as children would be given a one-year exemption from the statute of limitations. Regardless of how long ago the alleged abuse occurred, they could file suit in civil court.

At the year’s end, time limits on such claims would be restored, but with a wider window: Instead of a five-year period after turning 18, victims would have 10 years to file claims.

The bill would not lift the statute of limitations for criminal prosecutions of child abuse, which in most cases are the same as for civil complaints. For violent assaults like rape, there are no time limits on prosecution.

Many children’s advocates say guilt, shame and fear of the emotional toll on family members have often deterred victims from reporting sexual abuse until well into adulthood. The revelations of past abuse by priests that became a national scandal starting in 2002 prompted some to seek redress, only to discover they were barred by the statutes of limitation.

Marci A. Hamilton, a professor at the Benjamin N. Cardozo School of Law at Yeshiva University who has argued that states should remove all statutes of limitation on child sex abuse claims, said the principle is comparable to the way industrial pollution is treated under the law. “The consequences of toxic pollution may not be known or felt for years after the fact,” she said. “The same is often true for children who are sexually abused.”

But opponents of such unlimited time frames of liability contend that decades-old memories of childhood events are not reliable.

Foes of Assemblywoman Markey’s bill also say it unfairly singles out religious and private institutions, while leaving public schools virtually immune to the same potential liability.

The disparity is built into the legal protections granted under existing state law to all public workers and agencies: to sue a public employee or agency for damages of any kind, a person is required to file a claim within 90 days of the alleged injury. A victim of childhood sex abuse by a public school teacher, for instance, has 90 days after turning 18 to file notice of a claim.

Since the Markey bill would not extend that window, opponents claim that it discriminates. The Rev. Kieran E. Harrington, spokesman for Bishop DiMarzio, said that “a fair piece of legislation would treat all victims equally, and this bill does not do that.”

In response to those objections, Assemblyman Vito J. Lopez, a Brooklyn Democrat, introduced an alternative bill last month that would eliminate the proposed one-year suspension of the statute of limitations. Under his measure, the window for filing claims would be extended to seven years after the accuser turns 18, rather than the 10 years in Assemblywoman Markey’s bill.

Though he voted for her bill twice in past sessions, he said he had not realized the inequities in the new law until after a series of meetings he held in recent months. They included face-to-face talks with Bishop DiMarzio, he said, as well discussions with civil liberties advocates, members of the Legal Aid Society, and representatives of the Sephardic Community Federation and the United Jewish Organizations of Williamsburg, Brooklyn, which is in his district.

“You have three or four times as many kids in the public schools as in the Catholic schools,” Mr. Lopez said. “How is it fair if the law only penalizes these religious and private schools?”

Senator Eric T. Schneiderman of Manhattan, chairman of the Senate Codes Committee, which is scheduled to take up the bill as early as next week, said the disparity might be addressed in future legislation. But he added, “Just because it does not broaden the rights of victims 100 percent does not mean we should not try to broaden their rights somewhat.”

In past years, Assemblywoman Markey’s bill was never scheduled for discussion in any Senate committee, reflecting the unwavering opposition of the longtime Senate Republican majority leader, Joseph L. Bruno. He did not seek re-election in November, when Democrats won control of the Senate; the new majority leader, Malcolm A. Smith, supports the bill.

Asked for Archbishop Dolan’s view of the bill, and its potential impact on his tenure in New York, a spokesman for the New York Archdiocese said Wednesday that the archbishop was not immediately available to comment. Archbishop Dolan spoke out last year against similar legislation in Wisconsin. But at a news conference last month, he said he had not had time to study the New York bill.

Calls to representatives of the United Jewish Organizations of Williamsburg and the Sephardic Community Federation on Wednesday were not returned.

Senator Thomas K. Duane, a Manhattan Democrat and the bill’s lead sponsor in the Senate, said he was “extremely optimistic” about its chances.

He said that opponents’ claims of unfairness were not compelling, and that warnings of bankruptcy for religious institutions, which he dismissed as unlikely, missed the point.

“It’s not about money,” he said. “It’s about giving people the right to seek justice.”