Election after election, Democrats have raised the necessary money, gotten the needed attention and tried to win a Senate seat in Texas. They’ve talked football, chronicled their journeys across the vast state, highlighted their military heroism — and failed.

Now James Talarico, a young Democratic state representative and Presbyterian seminarian, is taking a new tack, unafraid to talk with anyone who will listen about his deep Christian faith and how it informs his liberal politics.

On Tuesday, Mr. Talarico officially joined the race for the seat currently held by Senator John Cornyn, entering a Democratic primary that already includes the former congressman and former N.F.L. linebacker Colin Allred — who unsuccessfully tried to unseat Senator Ted Cruz last year — and a former astronaut.

For anyone in Texas who has watched cable TV or listened to podcasts, Mr. Talarico’s pitch has a familiar ring. He spars on Fox News. He banters with Joe Rogan. And, he said in an interview, he thinks beating Republicans in the Trump era and turning Texas blue for the first time in three decades will mean embracing “compassion and sincerity and honesty and unity.”

“It’s been 10 years of this kind of Trumpian politics, politics as blood sport, politics as professional wrestling,” Mr. Talarico said. “The country is ready for something different.”

The 36-year-old former public school teacher is pursuing what is likely to be an uphill campaign. Mr. Allred is far better known, and the field may also include another former congressman, Beto O’Rourke, perhaps the most famous Democrat in the state.