Texas" Davis Is Expected to Enter Race for Governor State Senator Wendy Davis of Texas at the National Press Club in Washington last month. HOUSTON - Wendy Davis, the Texas state senator whose filibuster in June against an abortion bill backed by the state's powerful Republicans catapulted her to national political prominence, has told supporters and potential donors that she plans to announce next week that she will run for governor, according to Democrats in Texas and Washington. Ms. Davis's decision has the potential to turn the race to determine Gov. Rick Perry's successor into a rare competitive showdown between long-suffering Texas Democrats and the Republican conservatives who have ruled state politics for decades. She would enter the race as a substantial underdog, but her candidacy would represent the most serious challenge to the Republican lock on the office. Two Republicans, Mr. Perry and George W. Bush, have held the office since the party began its winning streak in governor's races in 1994, with Mr. Bush's victory over the incumbent, Ann W. Richards. For weeks, Ms. Davis's travels to Washington, her speeches, meetings with potential supporters and public statements have suggested her intentions. On her Twitter feed on Thursday she wrote: "A week from today, I'm announcing something big. Can you chip in now to show the strength of our grassroots network? Last week, she e-mailed supporters, telling them that she would answer the question about her political future next Thursday and that she was "excited about what we can do together in the future." The Democratic Governors Association, meanwhile, has been running a banner headline on its home page reading "Wendy's Big News." A spokesman for Ms. Davis said Thursday only that she had made a decision, and that it would be revealed next week. Matt Angle, a longtime adviser to Ms. Davis and the director of the Lone Star Project, a Democratic policy group, said he was looking forward to her decision, adding, "All of us believe that Wendy deserves the right to make that announcement herself." Until she makes that announcement there is no guarantee what her final decision will be. But, absent an official announcement, people involved in Republican and Democratic politics said word had spread in Austin of her intention to run and that some of the organizational planning and machinery for her campaign was already being put into place. Her campaign would be based in Fort Worth, a large portion of which she has represented in the State Senate. Her announcement next week will take place in the Fort Worth suburb of Haltom City, at the same coliseum where she received her high school diploma. Ms. Davis's Republican rival seems likely to be Greg Abbott, the Texas attorney general. He has raised more than $20 million and is tremendously popular among conservatives, many of whom support him for taking on the Obama administration on legal fronts including federal environmental regulations and the president's health care law. Most independent political analysts view Mr. Abbott as an almost unbeatable candidate, and the conventional wisdom is that Ms. Davis's campaign would be considered a success if she runs a close race in a state where Republicans hold every state office. But some Democrats say they are more optimistic. "I think her chances are very good," said Mark W. White Jr., a Democratic governor from 1983 to 1987 who defeated a wealthy Republican incumbent, William P. Clements, in 1982 but lost to him four years later in a rematch. I compare it to my chances of winning when I decided to run for governor. Everybody said it was impossible to do, and I was able to do it, and they're probably telling her the same thing. She's got the advantage that David had over Goliath. Ms. Davis's filibuster, which was watched online across the country, was an attempt to block the Republican-controlled Legislature from passing some of the toughest restrictions on abortion in the country. The bill ultimately passed, but her filibuster gave her and Democrats a boost of momentum and cash. Shortly before and after her filibuster, she received nearly $1 million in campaign contributions in just two weeks, much of it from people who gave her $50 or less. Political analysts said that was small change compared with the roughly $40 million she would need to raise to compete on a statewide level with Mr. Abbott, an ally of Mr. Perry's. "Abbott is an intelligent and disciplined candidate who is very unlikely to commit the type of unforced catastrophic errors that could cause him to be defeated," said Mark P. Jones, a political science professor at Rice University in Houston. It would take a political miracle for Wendy Davis to win. Republicans dominate Texas politics. They control both chambers of the State Legislature, and hold all statewide elected offices. The last time a Democrat was elected to statewide office was nearly 19 years ago, when Attorney General Dan Morales, Lt. Gov. Bob Bullock and a handful of others won re-election in 1994. "Democrats running statewide in Texas have lost by an average of 12 to 16 points for the better part of two decades," said Calvin Jillson, a political science professor at Southern Methodist University in Dallas. Some Democrats, however, note that for 105 years, from 1874 to 1979, an unbroken string of Democratic governors led the state. They and other analysts said that even if Ms. Davis were defeated, her campaign would lay the foundation for future wins and help revive the party, particularly as minorities grow as a share of the population. "Her entry into the race will be a shot in the arm for Democratic morale, but will also likely inspire a counter-reaction among the conservative wing of the Republican Party, especially social conservatives, who view Davis through the prism of abortion politics," said James Henson, director of the Texas Politics Project at the University of Texas at Austin.