EL PASO, Texas/WASHINGTON - Beto O'Rourke, the Texan who gained a national following with his long-shot election battle against US Senator Ted Cruz last year, will seek the 2020 Democratic presidential nomination, a source close to the campaign said on Wednesday.

O'Rourke, a 46-year-old former three-term US representative from West Texas, will make his announcement via video on social media at 7:30 am EDT (1130 GMT) on Thursday, the source said.

"I'm really proud of what El Paso did and what El Paso represents," O'Rourke said of his hometown in a text to TV station KTSM, which first reported his entry into the race.

"It's a big part of why I'm running. This city is the best example of this country at its best."

O'Rourke planned to follow his announcement with a trip to Iowa, the state that will hold the first Democratic nominating contest in February 2020.

With his presidential effort, O'Rourke is hoping to leverage the fame he gained with his Senate race. He was a heavy underdog when he challenged Cruz, a Republican, in mostly conservative Texas, but he quickly demonstrated an ability to draw capacity crowds and raise money from voters nationwide.

His Senate bid generated a torrent of media attention and excited voters in a party desperate for fresh political faces.

Reuters