WASHINGTON — Beto O'Rourke isn’t running for Senate again as many Democrats had hoped. But the people who helped the former El Paso congressman come closer to winning statewide office than any Democrat in a generation are now working to unseat Republican U.S. Sen. John Cornyn in 2020.

Many of the staffers from O’Rourke’s 2018 Senate campaign are now working with Cristina Tzintzún Ramirez, a progressive labor organizer in the crowded Democratic primary field vying to take on Cornyn. They include his former campaign manager, Jody Casey, and 20 other members of his campaign.

“I believe that Cristina’s incredible work ethic and community-focused approach will inspire and activate Texans, and will be the key to defeating John Cornyn in 2020,” Casey wrote in an online post, in which she describes first meeting Tzintzún Ramirez while working on O’Rourke’s Senate campaign.

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Tzintzún Ramirez will first face a field of nearly a dozen Democrats who have filed to run, including former Houston congressman Chris Bell, state Sen. Royce West, former Air Force pilot MJ Hegar and Houston City Council Member Amanda Edwards.

Multiple polls have shown that most Texans have little familiarity with any of the candidates in the race, and many of O’Rourke’s supporters held out hope he would jump into the Senate race after ending his presidential run last month. On Monday, Bell thanked O’Rourke for being “a progressive catalyst for change within the Democratic Party not only in Texas, but nationally as well.”

Cornyn, who is seeking his fourth term in the Senate, had long warned his supporters that O’Rourke might get into the Senate campaign. But that did not happen.

“While my opponents race to be the next Beto O’Rourke, we continue to build the largest grassroots army Texas has ever seen," Cornyn said in a statement last month as he filed his re-election paperwork. "Over the next year there will be a clear contrast: the successful Texas model of less government and more freedom, or Elizabeth Warren’s vision of socialized medicine, crushing taxes, and the Green Raw Deal.”

For subscribers: Beto O’Rourke casts a long shadow over 2020 U.S. Senate race in Texas

Democrats, however, hope they can build on O’Rourke’s momentum and unseat Cornyn, who himself has shown lackluster polling in recent months.

“This feels like ours to lose,” Hegar said on Monday. “The hands I’ve shaken, the yes I’ve looked into are Texans who are getting engaged for the first time or are open to hearing alternate solutions or voting for a Democrat for the first time.”

“The path ahead is very clear,” she said.

ben.wermund@chron.com