Two people with knowledge of the decision have told The Associated Press that Democrat Wendy Davis is running for Texas governor.
Two Democrats spoke to AP on condition of anonymity because they did not want to pre-empt her formal announcement scheduled for next week.
The 50-year-old Davis is the state senator who catapulted to national stardom this summer with a nearly 13-hour filibuster in the Texas Capitol that temporarily blocked new statewide abortion restrictions.
No other Texas Democrats have entered the governor's race. Republican Attorney General Greg Abbott announced his candidacy this summer and is the early favorite to succeed Gov. Rick Perry.
Perry is not seeking re-election after 14 years in office.