Gov. George E. Pataki announced Wednesday that he will not seek a fourth term, sidestepping an underdog battle and allowing him to launch a possible presidential bid in 2008.

"With pride in our accomplishments . . . I am announcing that I will not seek another term as your governor," Pataki said at a news conference in the state Capitol in Albany -- an announcement that rapidly echoed around the state and in political circles beyond.

Pataki, 60, decided not to seek a fourth term after staring his political mortality in the face. Several recent polls showed Pataki running 10 to 20 percentage points behind state Attorney General Eliot L. Spitzer, the Wall Street corruption buster who is the front-runner for the Democratic gubernatorial nomination.

Pataki was an obscure Upstate legislator when he scored a upset in 1994 by beating Mario M. Cuomo, a Democratic three-term governor with presidential aspirations. Pataki's term ends next year.

"George Pataki has learned something from Mario Cuomo: New York governors should never seek a fourth term," said Mitchell Moss, a professor at New York University's Wagner School of Public Service.

Pataki became something of a national model for how a Republican might survive and even thrive in a resolutely "blue" state. His aw-shucks style -- laconic not quite to the point of catatonic -- made him an elusive target. He rarely gave interviews or debated his opponents, and more than a few political rivals went to their political grave underestimating him.

Pataki also gave himself an ideological makeover. He won in 1994 stressing unabashedly conservative tax-cutting and pro-death-penalty themes. Over time, he played these down and evolved into a pro-labor, pro-environment, pro-abortion-rights and emphatically pro-spending politician of a stripe that in an earlier age was known as a Rockefeller Republican. He strengthened labor-organizing laws and signed lavish union contracts with state workers and a prescription drug plan for seniors. In the last election, Pataki's support from traditional Democratic voters -- organized labor and environmentalists, to name two groups -- eclipsed that of Nelson A. Rockefeller, the only four-term governor in New York history.

All of this came at a considerable cost. State spending has jumped 37 percent in the past five years, and the Democratic state comptroller has pointed out that New York faces an $11 billion shortfall in three years. And after seizing control of the rebuilding of Ground Zero in Manhattan, Pataki failed to meet deadlines and was forced to tear up and redo plans for the Freedom Tower.

Even today, few political types know how to draw his measure as a possible presidential candidate. Pataki on Wednesday would say only that "come 2007, I will follow a new path, find new challenges."

The temptation for some political consultants is to dismiss the governor as too liberal and too bland to survive a run through the Republican primaries. But the Republican Party has traditionally relied on a political marriage of two groups -- southern evangelicals and white northern Catholics. Pataki is Catholic and has been a loyal Republican soldier in national contests.

"George Pataki was early for George W. Bush, he knocked John McCain off the primary ballot in New York, and he raised lots of money for the party," said Hank Sheinkopf, a New York City-based political consultant. "He has a realistic due bill with the national Republicans."

That said, Sheinkopf is not humming "Hail to the Chief," saying Pataki seems interested in raising his name recognition.

Back in New York, Pataki has no clear political heir. When he took office in 1994, U.S. Sen. Alfonse M. D'Amato was the power broker of a powerful state Republican Party. Most of that has turned to dust. Democrats control all but one statewide office: the governor's seat.

"The whole Northeast is going bluer and bluer," said Maurice Carroll, polling director for Quinnipiac College.

George E. Pataki left open the possibility of a presidential run.