Liberal political organizer David Brock is reportedly in discussions with Democrat operatives about launching an effort to thwart Sen. Bernie Sanders’ (I-VT) prospects of winning the party’s nomination for president in 2020.

According to the New York Times, Brock, founder of the left-wing American Bridge super PAC, is one of several left-leaning operatives concerned about Sanders’ apparent status as the Democrat frontrunner.

“The Bernie question comes up in every fund-raising meeting I do,” Brock told the Times.

“There’s a growing realization that Sanders could end up winning this thing, or certainly that he stays in so long that he damages the actual winner,” said Brock, who backed Hillary Clinton’s failed presidential bids in 2008 and 2016. Brock told the Times that he has spoken to fellow operatives about a possible anti-Sanders campaign and says it should launch “sooner rather than later.”

Brock did not reveal which operatives have been involved in these discussions.

In an interview with the Times, pollster Howard Wolfson seemingly concurred with Brock’s sense of urgency, saying that “People underestimate the possibility of [Sanders] becoming the nominee at their own peril.”

However, Brock concedes that an effort to prevent Sanders from winning the nomination backed by big-money Democrats could potentially be exploited for the democratic socialist’s political gain.

“You can see him reading the headlines now,” Brock said. “‘Rich people don’t like me.’”

Any campaign supported by Brock to stop Sanders would be a reversal of a January 2017 promise to support the senator after opposing him during the 2016 Democrat presidential primary.

“I’m with you in the fight ahead,” Brock wrote in a blog post of Sanders on Medium.

“At times during the Democratic primary, I was criticized for being too aggressive in my support for Secretary Clinton — and rightly so,” he added. “Looking back, I recognize that there were a few moments when my drive to put Hillary in the White House led me to take too stiff a jab. I own up to that, I regret it, and I apologize to you and your supporters for it.”

The Sanders campaign has not commented on Brock’s plans to oppose his nomination.

Meanwhile, Sanders and former Vice President Joe Biden hold a substantial lead over their Democrat White House rivals, according to an Emerson national poll released Monday. Sanders topped the survey with 29 percent of Democrat primary voters’ support, while Biden placed second with 24 percent. South Bend, Indiana, Mayor Pete Buttigieg ranked third at nine percent.

Earlier this month, the Sanders campaign announced it raised $18.2 million over the first six weeks.