A battle is erupting between New York and New Jersey, with Governor Corzine threatening to sue over Mayor Bloomberg’s congestion pricing plan, saying recent changes to it are outrageous and would unfairly penalize drivers from New Jersey.

At the center of the political road rage is a new provision requiring the Port Authority of New York and New Jersey to contribute $1 billion toward transportation projects. If the money doesn’t come in, drivers entering the city from New Jersey would be charged an extra fee on top of the tolls they already pay, forcing them to pay more than other drivers traveling to Manhattan.

The threat of legal action from Mr. Corzine comes at an inopportune time for the mayor, who is nearing a deadline to win support for the traffic plan in Albany.

In a final push to secure votes, at least four Bloomberg officials trolled the halls of the Capitol yesterday, making a case for congestion pricing to lawmakers. The city’s transportation commissioner, Janette Sadik-Khan, is expected today in Albany.

The plan must be approved by state lawmakers by April 7 for the city to receive $354 million in federal transportation funding.

Mr. Bloomberg has support from Governor Paterson and the majority leader of the Senate, Joseph Bruno, but the speaker of the Assembly, Sheldon Silver, has refrained from backing the proposal. When Mr. Silver told Democratic lawmakers in the Assembly that they would begin talks about congestion pricing today, the announcement was met with boos and hisses, an Assembly member said.

Albany lawmakers said yesterday that there isn’t enough support for congestion pricing to pass, but they aren’t ruling out the possibility that Mr. Bloomberg’s lobbying effort will convince enough legislators to back the plan in the final days and hours.

“I think there are people who haven’t made up their minds. There are people waiting to be bought,” a Democratic assemblyman said.

The governor visited New York City yesterday afternoon to celebrate his wife’s birthday and attend a private meeting. He returned to Albany by the evening for budget talks, a spokesman for Mr. Paterson said.

The City Council approved congestion pricing by a vote of 30 to 20 on Monday, with members saying that offers of political support from Mr. Bloomberg and assurances of transportation improvements and other issues helped secure the votes he needed.

Under the plan, most drivers entering Manhattan below 60th Street between 6 a.m. and 6 p.m. on weekdays would be charged $8, but congestion pricing could undergo further revisions in the coming days as critics and supporters attempt to shape the bill to their liking.

A City Council member who voted in favor of congestion pricing, Alan Gerson, is urging state lawmakers to carve out a host of exemptions to the plan, including provisions to exempt drivers seeking medical care, exempt vehicles owned and operated by non-profit organizations, and create a sliding scale system that would charge drivers a fee based on their income level.

The threat of an additional fee for drivers entering the city from New Jersey was a concession added to the legislation over the weekend to appease critics who said it wasn’t fair that a group of drivers wouldn’t face any additional costs if congestion pricing were approved. The plan had called for existing tolls to be deducted from the congesting pricing fee, so some drivers entering from New Jersey wouldn’t have had to pay anything more under the original proposal. Mr. Corzine said yesterday that he will only support a plan that is fair to New Jersey commuters and he said this one is not.

“I am dismayed at the attempt by the New York City Council and New York state lawmakers to politicize the selection of Port Authority capital projects — a cooperative, bi-state process that has served the people of New York and New Jersey so well for so many years,” he said in a statement.

He said he is particularly disappointed at the threat to impose a toll surcharge on New Jersey drivers who are already subject to congestion pricing by the increased tolls they are paying to use the George Washington Bridge and the Lincoln and Holland Tunnels. “Unless this plan treats all drivers fairly, I am prepared to pursue legal action to protect New Jersey commuters from this outrageous action,” Mr. Corzine said. The Newark Star-Ledger reported his comments yesterday.

The revision calls for drivers entering the city from New Jersey to be charged an additional $3 to $4 on top of the tolls they already pay, if the Port Authority does not contribute the $1 billion the congestion pricing legislation is seeking.

Between 6 and 9 a.m. and 4 and 7 p.m., drivers from New Jersey with an E-ZPass pay $8 to enter Manhattan. They pay $6 during off-peak hours. Under the plan approved by the City Council with Mr. Bloomberg’s backing, drivers entering the city from New Jersey would be charged an extra $3 during peak hours and $4 during off-peak hours.

A spokesman for the mayor, John Gallagher, pushed back against Mr. Corzine’s threat and defended congestion pricing.

“We don’t understand why it’s okay for the New Jersey Governor to hike tolls on New York cars on the Turnpike and Parkway to balance his state’s budget, but New York can’t raise revenue dedicated expressly for mass transit improvements for commuters across the region. That seems to be a double standard, and we’re certain that our plan is not only fair and equitable, but also that it will withstand any legal challenges he brings,” he said in a statement.

About 140,000 commuters enter New York City from New Jersey, but many of them live in New York state, a spokeswoman for the Port Authority said. She could not immediately say how many drivers from New Jersey commute to the city each day.

New York’s highest state court, the Court of Appeals, in 2000 threw out a commuter tax that New York imposed on those from Connecticut and New Jersey who commuted to New York City. The tax had applied also to New York State residents who commuted from the suburbs to the city, but in 1999 the state legislature repealed the commuter tax for New York residents, leaving it only to apply to those from New Jersey and Connecticut. The court said the tax on out-of-state commuters violated both the privileges and immunities clause and the commerce clause of the federal constitution.