State Rep. Joaquin Castro, D-San Antonio, who planned to run for Congress in CD-35, one of Texas' four new U.S. House districts, confirmed Friday evening that he will instead run to succeed retiring U.S. Rep. Charlie Gonzalez, D-San Antonio, in CD-20.

Gonzalez, who was elected in 1998 to the seat long held by his father, Henry B. Gonzalez, announced earlier in the day that he would not run for re-election.

Castro told the Tribune that he had a "good conversation" with Gonzalez around 5 p.m. Friday and that "he encouraged me to run." Castro's house in actually in CD-20 — he would have had to move into CD-35 — and he was born, raised and educated there. The district is also where his grandmother settled when she came to the U.S. almost 100 years ago.

"Like he and his family, I have a very long history in the district," Castro said. "I will be honored to continue their wonderful legacy of service."

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Castro will formally announce his intention to run in CD-20 at a press conference at 3 p.m. Saturday — two hours after Gonzalez makes his plans to retire official at his own press conference. Castro will be introduced by state Sen. Leticia Van de Putte, D-San Antonio, who is endorsing his candidacy, as are his fellow state Reps. Trey Martinez Fischer and Mike Villarreal, also San Antonio Democrats.

No other Democrats are said to be looking at the CD-20 race, and sources say Gonzalez could endorse Castro sometime soon, effectively passing the baton from one iconic political family to another. Castro's brother, Julian, is in his second term as mayor of San Antonio and is widely considered a rising political star.

Back in CD-35, former U.S. Rep. Ciro Rodriguez is expected to announce his candidacy on Tuesday; he previously held the CD-23 seat but lost his general election race in 2010 to Republican Francisco "Quico" Canseco. Sources say Sylvia Romo, a former state lawmaker and currently the Bexar County Tax Assessor, is also considering a CD-35 bid.

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