ALBANY — The Paterson administration will go ahead with a plan to lay off thousands of state workers beginning Jan. 1 — now that other cost-saving measures have been rejected by either labor unions or the courts.

Gov. David A. Paterson on Monday called layoffs a “last resort” but claimed union leaders have failed to help him come up with $250 million in payroll savings he wants as part of the state’s effort to reduce the budget’s $9.2 billion deficit.

The governor said he has a “sinister theory” that union heads might not be so concerned about layoffs because those workers—unlike a larger group affected by furloughs or a pay freeze—would not then be able to vote in union elections.

“Sometimes I wonder if I haven’t been pushed into this,” Paterson said, referring to union leaders.

Steve Madarasz, a spokesman for the Civil Service Employees Association, called the governor’s theory “pure nonsense.”

“Nobody wants to see layoffs,” Madarasz said.

Paterson administration officials in late March told The Buffalo News of a plan for “massive” layoffs come Jan. 1 if other payroll cost-cutting measures were not approved.

Unions have rejected a pay freeze, and last week a federal judge ended the governor’s attempt to furlough state workers one day a week for eight weeks. The administration brought back the idea with the New York Times on Monday, and aides again confirmed the existence of a layoff plan.

The first day of January is when a memorandum of understanding between the state and its two largest unions — CSEA and the Public Employees Federation — expires. That memo is a pledge by a Paterson administration official that the state would not lay off workers, or even threaten to do so, until after Jan. 1 in return for the unions last year supporting cost-savings in a pension system for future state workers.

Paterson said he does not want to contribute to the state’s job loss numbers as it tries to emerge from a recession by going ahead with layoffs and that spreading out pain among the work force — such as through a pay freeze—would be fairer to state employees than laying off parts of the work force. He did not put a number on potential layoffs and said the plan is only in the beginning stages.

Paterson leaves office Dec. 31, and he said his effort is to have a plan in place before his term ends that the next governor can use to reduce the work force and immediately achieve cost savings early in 2011.

Madarasz, the CSEA spokesman, called the layoff threat “absurd and counterproductive” and said Paterson should spend his time negotiating a state budget deal instead of making moves against his work force in the media. “All he’s doing is making people crazy about things that may or may not happen eight months down the line,” Madarasz said.