By Marice Richter

FORT WORTH, Texas (Reuters) - The widow of a slain Navy SEAL whose story was turned into the hit movie "American Sniper" has become a prominent figure in Fort Worth Republican politics even though her name does not appear on Tuesday’s primary ballot.

Taya Kyle, the wife of Chris Kyle, is campaign treasurer for a Republican opponent of longtime Tarrant County Sheriff Dee Anderson, the lawman seen as the face of the manhunt for “affluenza” teen Ethan Couch.

Kyle is also in a dispute with her late husband’s former business partner Bo French, who is running as a Republican for a Texas House of Representatives seat from the same county.

Lawyers for Kyle sent a cease-and-desist letter to the French camp last week calling on it to stop using her husband's name and likeness in campaign materials.

“Bo (is) abusing the name of my late husband, a beloved Son of Texas, and a hero to the nation, in an attempt to manipulate voters,” Kyle said in a statement on social media. She did not respond to requests to speak about her political activism.

"Her experience with public exposure and scrutiny has taught her not to let her guard down," said Republican political strategist Bill Miller. "She's become a very formidable woman."

Chris and Taya Kyle have become stars of the state's Republican establishment, with Governor Greg Abbott setting up a day to honor the memory of Chris Kyle, who was killed in 2013 by a troubled veteran he was trying to mentor.

Taya Kyle last year endorsed former Governor Rick Perry in his unsuccessful bid for the Republican presidential nomination. She now endorses U.S. Senator Ted Cruz of Texas.

In the sheriff's race, she may be the difference in the campaign of Bill Waybourn, a former suburban Fort Worth police chief, analysts said.

Waybourn, backed by the conservative Tea Party movement, is challenging Anderson, a fellow Republican, who gained national attention in calling for the apprehension of Couch. The teen, whose lawyer said his wealth distorted his moral compass, fled to Mexico in December apparently to avoid apprehension for violating the probation deal that kept him out of jail for a drunken driving wreck in 2013 that killed four people.

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Kyle, 41, has not indicated any intention to seek elective office, but analysts said that should not be ruled out.

"Once someone gets involved and gets their hands wet in politics, it’s hard to get out," Miller said.

(Reporting by Marice Richter; Writing by Jon Herskovitz; Editing by Peter Cooney)