Yet some of the president’s big-money backers say they aren’t interested in bankrolling an effort aimed at propping up Sanders. They worry his potential strength in a general election is being badly underestimated, much as Democrats wrongly discounted Trump four years ago.

The biggest fear about Sanders is that he could threaten the president’s monopoly on the outsider mantle in a way other Democrats in serious contention for the nomination cannot. Others express unease about Sanders’ energized following and worry that, as an unconventional, candidate he could inject an unpredictable dynamic into the contest. They, too, see potential parallels to Trump in 2016, when he attracted a wave of new voters.

Others say Sanders has struck a nerve with his focus on kitchen table issues both parties have long overlooked. Last week, Trump favorite Tucker Carlson used his Fox News show to warn that Sanders’ push to forgive student debt could win “many thousands” of past Trump voters.

“Bernie Sanders poses the greatest risk because we are still in an anti-establishment era for presidential elections,” said North Carolina Rep. Mark Meadows, who is widely regarded as a potential future Trump White House chief of staff.