Ruben Gallego is left's favorite to primary Sinema

Progressives are already laying the groundwork for a potential primary challenge, and one campaign, Run Ruben Run, has set its sights specifically on recruiting Gallego into the race.

For now, at least, many Democrats remain wary of the early efforts to challenge Sinema from the inside. They’re holding out hope that she reverses course and gets behind the reconciliation bill. But in conversations with The Hill, half a dozen Democratic activists and party insiders said that a primary is not off the table and pointed to Gallego as a top prospect if Sinema continues to hold out on the party’s key legislative priorities.

“Ruben is a strong progressive leader who has accomplished a lot of things in a short time,” Steven Slugocki, the former Maricopa County Democratic Party chair, said. “He’s passed a lot of bills, he’s a veteran, he’s a Latino. He’s a strong voice in Congress who’s getting things done. He has a lot of support in the party as well as with Democrats across the state.”