By Jeremy W. Peters

ALBANY — He is not campaigning for office — at least not yet — but that has not immunized Gov. David A. Paterson against the political attack ad.

Starting on Tuesday, the left-leaning Working Families Party and the education advocacy group Alliance for Quality Education began broadcasting commercials in the state’s biggest television markets that assail the governor for his support of a cap in property tax increases.

(Watch the Commercial: Commercial [QuickTime] or Commercial [MPEG])

The commercials, which are being broadcast at a cost of $1.5 million and will run repeatedly on cable and network television from now until Aug. 19, the day the Legislature convenes for a special session, refer to the cap as a “gimmick” and a “scheme.”

The measure, which would place a mandatory limit on property tax increases, was approved by the State Senate last week. In the State Assembly, however, a similar bill faces an uphill battle.

The ad campaign represents an aggressive attempt by the Working Families Party, which would seem to be a natural political ally of the governor’s, to try to influence the public dialogue on property taxes and the New York economy as a whole.

Mr. Paterson, a Democrat, has made a property tax measure one of the central policy objectives of his young administration. He has crisscrossed the state in recent weeks on a campaign-style tour to promote the plan.

“The governor does have a big megaphone,” said Dan Cantor, executive director of the Working Families Party. “This is a bad idea that will harm our schools, and we want to drive that home as the Legislature heads back into session.”

Billy Easton, executive director for the Alliance for Quality Education, said, “Millions of New Yorkers will see this ad buy multiple times, and it’s our hope that Governor Paterson will hear from them.”

The 30-second commercial opens to ominous-sounding piano music as a narrator says, “Everyone agrees property taxes are a problem, but Gov. David Paterson’s property tax gimmick is the wrong answer.” The narrator then cites what the Working Families Party and the Alliance for Quality Education say were some of the effects of plans to cap property tax increases in other states: larger class sizes, billions of dollars in education cuts and laid-off teachers.

The commercial ends with the narrator saying, “Tell David Paterson hurting schools is the wrong answer.”

Mr. Paterson’s office responded to the advertisement on Tuesday in a written statement calling the cap plan “sensible” and citing progress by students in Massachusetts, where a cap on increases was put in place. It also tied the cap in with the governor’s plan to turn New York’s economy around.

“There is widespread recognition among New Yorkers that runaway increases in property taxes are deeply hurting our state,” the statement said. “Anyone who does not acknowledge this trend is out of touch with working families. The longer we wait to approve a property tax cap, the more we will hamstring New York from reaching its full economic potential.”

The timing and size of this advertising campaign raised questions about whether opponents of the plan suddenly feared that it was gaining momentum.

“We do not see a groundswell of support in the Assembly for the tax cap,” said Bob Master, a co-chairman of the Working Families Party. “Nevertheless, you know, we want to send a clear message to the governor and to all members of the Assembly, and really to all citizens of the state, that this tax cap gimmick is not a solution. It is only a sound bite that has not been thought through.”