Comptroller and gubernatorial hopeful Carole Keeton Strayhorn turned her back on the Republican Party Monday, announcing that she'll seek the state's top job as an independent candidate.

The move allows Strayhorn, 66, to escape a potentially ugly battle against Gov. Rick Perry before the March 7 GOP primary election.

Known as "One Tough Grandma," Strayhorn has been a harsh critic of Perry's leadership over the past couple of years. Monday's announcement all but guarantees Perry will be the Republican candidate on the November ballot.

"I am a Republican," she said Monday, with husband, Ed, and three granddaughters at her side. "But I know we must set partisan politics aside and do what's best for Texas. That is why I am running for governor as a Texas independent."

Robert Black, a campaign spokesman for Perry, said the switch to independent is a concession that Strayhorn could not win the GOP primary and called the move "transparent political opportunism."

"Carole Strayhorn's decision to leave the GOP is a direct response to Governor Perry's strong leadership and support and an admission that she would have been defeated in the upcoming GOP primary by those who know her best: Texas Republican voters," Black said.

Strayhorn filed her declaration of intent to run as an independent with the state's Secretary of State's office on Monday, the deadline to enter the 2006 elections.

If elected, Strayhorn would be the first independent Texas governor since Sam Houston.

"Texas belongs to no special interest group, no special political credo, no special individual," she said.

Kinky Friedman, the kooky mystery writer and musician, also is seeking the Governor's Mansion as an independent.

To be listed as an independent candidate on the November ballot, one must gather 45,540 signatures in the spring from registered voters who didn't vote in either the Democrat or Republican primary or any primary runoff in April. The day after the primary election, independent candidates have 60 days to gather signatures, less if either race results in a runoff. The Secretary of State's office must then verify the signatures, which will be disqualified if they appear on more than one petition.

Strayhorn continued her criticism of Perry, blaming him for creating partisan division in Texas politics and for repeatedly failing to fix the state's public school funding problem.

"He has given us higher property taxes, bigger government, higher insurance rates, toll roads, has abandoned our border and ignored our broken schools," Strayhorn said.

Both are former Democrats who switched to the GOP in the 1980s as the party rose to political dominance.

Strayhorn announced last summer that she would challenge Perry. She was elected as the state's first woman comptroller in 1998. As comptroller, Strayhorn is the state's chief financial officer and controls how much money is available for lawmakers to spend.

Before being elected comptroller, she served on the three-person Texas Railroad Commission, a statewide-elected post.

Two of her four sons serve in President Bush's administration. Scott McClellan is White House press secretary, and Dr. Mark McClellan is administrator of the Centers for Medicare and Medicaid services. One of her sons, Brad, serves as her campaign manager. The other son, Dudley, is assistant general counsel for the State Bar of Texas.

Strayhorn also has five granddaughters.

The former Austin mayor married her high school sweetheart Ed Strayhorn in January 2003.

In the Democratic race, the main candidates are former Congressman Chris Bell and former Texas Supreme Court Justice Bob Gammage.

While Strayhorn insists she's still a Republican, the Texas GOP disagrees.

"Today the truth has come out: Carole Strayhorn is no Republican," said Tina Benkiser, chairwoman of the Republican Party of Texas. "Grassroots Republicans should be outraged that Carole Strayhorn has lied, deceived and now abandoned the very people who put her in office all for her own selfish ambition."