ALBANY – Governor Pataki is picking another fight with the Legislature, vetoing a budget-reform bill that the Assembly and Senate passed unanimously earlier this year.

Mr. Pataki argued the bill would not end New York State’s 20-year streak of late budgets, as its authors promised, but would actually give lawmakers a new incentive to delay. He also cited technical flaws that he said would put state government at risk of defaulting on debt and shutting down for lack of spending authority.

The leader of the Assembly Democrats, Speaker Sheldon Silver of Manhattan, called Mr. Pataki “an obstacle to government reform” and said he was hopeful that the Senate would agree to an override.

The Republican Senate majority leader, Joseph Bruno of Rensselaer County, made no such commitment, saying only that he would discuss the matter with his conference at a meeting this week.

The budget-reform legislation, which is coupled with a constitutional amendment that could go to voters next November, would shift the balance of power over state finances, giving the Legislature more leverage in its annual haggle with the governor.

Among other provisions, the legislation would delay the start of the fiscal year by one month, to May 1, automatically impose a contingency budget if lawmakers do not approve a new spending plan by that date, and set up an “independent budget office,” appointed by legislative leaders, to estimate the cost of spending programs and forecast revenues.

Proponents – including Common Cause, the League of Women Voters, the Citizens Union, and the New York Public Interest Research Group – argue that the reforms hold the promise of breaking the streak of late budgets, which annually disrupts funding for state programs, local governments, health-care providers, and nonprofit groups.

Critics, including the Business Council of New York State and the Citizens Budget Commission, say the new procedures would actually worsen the situation by taking away some of the governor’s traditionally tight control over financial affairs.

Mr. Pataki said he is particularly concerned that lawmakers, once the fiscal year begins, would no longer be bound by the template of the governor’s budget proposal and could draft a new spending plan from scratch.

“It would almost guarantee a late budget every single year,” he said at a news conference to announce the veto. “Once that contingency budget kicks in, the entire power changes to the Legislature, for them to write and forward their own budget proposal. That creates an incentive, obviously, for the Legislature to wait until the expiration of the deadline.”

The legislative director of Nypirg, Blair Horner, disputed Mr. Pataki’s argument, saying the governor would retain a line-item veto over whatever the Legislature adds to the contingency budget against his will.

“There’s no doubt that it changes the relationship” between the executive and legislative branches, Mr. Horner said. “But you have to start with what’s happening now: We have 20 years of late budgets, growing debt. The Legislature has come up with a solution that means negotiations will occur more speedily.”

He also questioned Mr. Pataki’s decision to raise objections in November, when lawmakers outlined their proposal in March and passed it in June.

“Given his track record, it’s an open question as to whether or not he’s serious about making budget reform happen or just wants to maintain his powerful status quo,” Mr. Horner said. “If he’s serious about reform, they can work it out this week. If he’s not, they should override him.”

The legislative battle over budgeting power parallels two lawsuits between Mr. Pataki and Assembly and Senate leaders, which are to be heard today by the state’s highest court, the Court of Appeals.

Also yesterday, Mr. Pataki vetoed a second bill that would have required the state to collect state taxes on gasoline and cigarettes that retailers on Indian reservations sell to non-Indians.

The governor said he prefers to negotiate the issue with Indian tribes as part of broader talks over land claims and casino rights – noting that a tentative agreement he reached last week with one tribe would resolve the issue.

“Now more than ever I am convinced that a positive outcome to the sales tax collection issue and other issues of mutual importance will only be achieved through cooperation, not confrontation,” the governor said in his veto message.

The governor’s decision was criticized by anti-smoking activists and tobacco retailers, who said the availability of tax-free cigarettes undermines public health efforts, hurts non-Indian stores, and costs the state hundreds of millions of dollars in revenue.

“The failure to collect the taxes on the Indians has lead to real deprivation in the retail sector of the state and of the city,” said a spokesman for the Neighborhood Retail Alliance, Richard Lipsky. “It’s unfair and there’s no possible public policy reason to veto this legislation that we can see.”