ALBANY — The Legislature’s decision to install one of its own members as comptroller could end up working to Governor Spitzer’s advantage by helping him to draw greater public support behind his political agenda.

Defying the governor, lawmakers yesterday elected as comptroller Thomas DiNapoli, a career Democratic assemblyman from Nassau County who was the favored choice of Speaker Sheldon Silver but was not among the candidates recommended by a special screening panel created under an agreement by the governor and legislative leaders.

Almost three-quarters of the Legislature voted for Mr. DiNapoli, including almost all of the Democratic Assembly and the Republican Senate majority. Senate Democrats led by Malcolm Smith sided with Mr. Spitzer by voting for the New York City finance commissioner, Martha Stark, one of three candidates put forward by the panel.

Before embarking on a tour around the state to promote his $120 billion budget, Mr. Spitzer yesterday unloaded a blistering criticism of the Legislature for disobeying his command that it choose a comptroller from a list of three candidates recommended by the panel.

“We have just witnessed an insider game’s of self-dealing that unfortunately confirms every New Yorker’s worst fears and image of all that goes on in the Legislature,” Mr. Spitzer said in a prepared speech. “Legislators and their leaders had an opportunity to rise above and show they have listened, learned, absorbed, but they did just the opposite. They returned to the cocoon of the Albany status quo that has driven their behavior for too long.”

The governor’s denunciation of the Legislature was a sharp signal of his intent to undermine lawmakers by casting them as enemies of the structural changes that he intends to impose on Albany.

The Legislature has long been a foil for New York governors frustrated by impasses. But Mr. Spitzer is attacking it as an executive with a 75% approval rating whose political strength was demonstrated by his success in orchestrating the victory of Senate candidate Craig Johnson, whose win in Tuesday’s special election on Long Island put the Republican control of the Senate into even greater jeopardy.

Delivering an ominous warning to lawmakers, Mr. Spitzer suggested that he is prepared to use his political machine to topple sitting lawmakers who don’t go along with his plans.

“My belief is that I will be effective as a voice for reform when I carry this message to the public and when I participate in every effort to the get the public to send to the Legislature individuals who understand the reform we are seeking,” he said.

Mr. Spitzer said he would “campaign against incumbents, Democrat or Republican, when I believe there is a better candidate.”

To Albany observers, Mr. Spitzer’s remarks were further evidence of his desire to be a competing political force within the Legislature, where power and patronage flow from the two longtime legislative leaders, Mr. Silver and the Republican Senate majority leader, Joseph Bruno.

“He’s evidently determined to be a player within the internal operation of the Legislature and will likely demonstrate a willingness to place his political muscle behind those who are willing to stand with him in defiance of legislative leaders,” a former Democratic assemblyman from Rockland County, Ryan Karben, said.

After the joint-session vote, lawmakers sought to downplay the rift between them and the governor and defended their choice of Mr. DiNapoli as one made on merit. Mr. DiNapoli, 52, who has a loyal base in North Hempstead, has served in the Assembly since 1987, including a 15-year stint as a member of the Ways and Means committee, which deals with budget and taxing issues. In the Assembly, he is known as a consensus builder and a champion of environmental preservation.

“It was clearly a vote for integrity, intelligence, and ability,” Mr. Silver told The New York Sun. “We are in agreement with the governor on a lot of his agenda. If there was a disagreement here, he should treat it as a blip on the radar screen and just go forward from there.”

The source of the disagreement lies in the process for picking a comptroller to replace Alan Hevesi, a convicted felon who resigned in disgrace after being elected for a second term in November. Although lawmakers have the power to vote to fill a vacancy in the office, they reluctantly agreed to set up a screening panel composed of three former state and city comptrollers after Mr. Spitzer demanded a greater say in the process. Lawmakers balked at the agreement after the panel came back with only three candidates, none of whom were members of the Legislature.

After taking the oath of office in the comptroller’s headquarters on State Street, Mr. DiNapoli, who will now oversee the state’s $145 billion pension fund, defended his credentials and dismissed the turmoil of the selection as “something for historians to write about.”

“I’m going to call the shots as I see them. I don’t intend to be anybody’s lapdog. I intend to be the watchdog,” he said, prompting applause and cheers from more than a dozen senators and Assembly members who came to witness his swearing-in after voting for him hours earlier.