The decision by former Gov. Tom Ridge to forgo next year's Senate race ends a brief but intriguing subplot in an already tangled political saga.

Mr. Ridge's announcement yesterday removed a potential challenge for all of the remaining contenders in the 2010 race. The former Erie congressman would not have been assured of victory in either the primary or general elections -- the state's Republican and overall electorates have shifted significantly in the 15 years since he last faced a contested primary. But Mr. Ridge, war hero, two-term governor and the nation's first Homeland Security secretary, would clearly have been a formidable candidate.

In a statement released yesterday, Mr. Ridge, who now heads a global security consulting firm, said, "The 2010 race has significant implications for my party and that required thoughtful reflection.

"To those who believe the Republican Party is facing challenges; they are right," he said. "To those who believe that the Democratic Party is without its own difficulties, they're are wrong."

The statement did not cite any specific reason for Mr. Ridge's decision.

Mark Holman, Mr. Ridge's longtime chief aide and confidante, said he sensed that part of his motivation was the difficulty of shifting focus to being a junior member among 100 legislators after years in executive roles in Harrisburg and Washington.

"I think legislative service was not as interesting to him at this point," Mr. Holman said. "He enjoys being a citizen now; so it was a decision to remain a private citizen and to remain [politically] active in other ways.

"This is one of those things that happen in politics and life that is unexpected," he said of the decision-making that led to yesterday's announcement. Mr. Holman said the former governor, who still maintains a home in Erie while spending most of his time in the Washington area, had not hinted at a final decision as late as Wednesday evening.

But in another round of calls yesterday morning, he told close friends and political allies that he had opted to forgo the race.

After Sen. Arlen Specter's game-changing decision to defend his seat as a Democrat, a variety of influential Republicans saw Mr. Ridge as a moderate alternative to former Rep. Pat Toomey, the fiscal conservative who nearly defeated Mr. Specter in the 2004 GOP primary.

Some conservative activists had already begun sniping at Mr. Ridge, noting his pro-choice views and relatively moderate overall stance. Those same issues had promoted widespread opposition in the conservative wing of the party when the Vietnam veteran was a reported candidate-to-be on the GOP ticket as vice president in 2000 and 2008.

Several early polls showed Mr. Ridge as the stronger general election candidate against Mr. Specter.

Intriguingly, however, in an appearance last night on MSNBC's "Hardball," Mr. Ridge declined to disclose his preference in a potential Toomey-Specter matchup.

"Now, if you had to vote between Toomey, the conservative Republican, or Specter, the ex-Republican, who would you vote for?" said Chris Matthews, who at one point had himself considered running for the Specter seat.

"It's a wonderful country, this America. It's called a secret ballot," Mr. Ridge replied.

"Come on!" the host demanded, according to an MSNBC transcript.

"You got my answer, Chris! That's hardball," Mr. Ridge said.

Mr. Ridge's decision leaves Mr. Toomey and Peg Luksik, a Johnstown conservative activist, as the only declared candidates in the GOP race. The absence of the powerful Ridge name, however, might make the GOP contest more tempting for other Republicans, such as U.S. Rep. Jim Gerlach, R-Chester, who has formed an exploratory committee for the race for governor. After Mr. Specter's bombshell party change last week, Mr. Gerlach issued a statement that appeared to open the door to a switch to the Senate race.

"Congressman Gerlach has been getting a lot of calls and support in his statewide campaign," said his political director, Mark Campbell. "When Sen. Specter changed parties, people began to encourage him to think about running for the U.S. Senate. ... For the time being, the question [of Senate or governor's race] is open but the primary focus is the gubernatorial exploratory committee."

Mr. Toomey issued a statement praising Mr. Ridge as a "true patriot and a leader," and portraying the former governor's political views as consistent with his own.

Citing Mr. Ridge's praise for limited government and lower taxes, he said, "I agree with Gov. Ridge's statement 100 percent. That is exactly the message I will take to the people of Pennsylvania in my campaign for the U.S. Senate."

Mrs. Luksik shrugged off the news.

"I feel like I'm looking at a merry-go-round. They can't make up their minds, these men," she said. "Whatever they decide, I'm going to be here through next year's primary season, and I'll be here waiting for them."