Fort Dodge, Iowa (CNN) Far away from his native Texas on Saturday, Julián Castro was greeted by a familiar sign from home.

A woman who donned a University of Texas at San Antonio T-shirt approached the 44-year-old former mayor of San Antonio. A mother of a UTSA graduate, she beckoned Castro for a photo, throwing up the famous Texan hand sign.

"You know, I have to say, I felt at home coming in, walking in, and there's a (UTSA) shirt," Castro said to a jovial crowd of 70 door-knockers that amassed in the front office of the Webster County Democrats' headquarters to support J.D. Scholten, a candidate for Iowa's 4th Congressional District.

This was the second trip to Iowa since August for Castro, a former housing and urban development secretary in the Obama administration. Officially, it's one of his many stops across the country to rally Democrats in an effort to flip the House and possibly the Senate back to blue, but Castro's visit once again stoked speculation that he, too, would join a plethora of politicos thought to become possible 2020 contenders.

This month, New Jersey Sen. Cory Booker finished his first swing through the Hawkeye State, and fellow Democratic Sen. Kamala Harris of California is set to make her entrance into the Iowa field this week. Vermont independent Sen. Bernie Sanders, who fell short of the Democratic nomination in 2016, will stump in the state next week.

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