Emily Larsen of the Washington Examiner asks whether Vermont Sen. Bernie Sanders has reached the pinnacle of his presidential campaign popularity.

Socialist Bernie Sanders, facing sharp competition on his left, is seeing support flag for his 2020 Democratic presidential bid.

The independent senator from Vermont dipped to 13% support in a Fox News poll of Democratic presidential primary voters released Sunday, still in second place behind former Vice President Joe Biden, but down from 17% in May and 23% in March. An Economist/YouGov poll released last week found Sanders had 12% support in the crowded field, down from 15% the week before and in third place behind Sen. Elizabeth Warren, D-Mass., who had 16% support.

Democratic strategist Mary Anne Marsh said Sanders’ support has passed its peak after an early bump of soft support due to residual name recognition from his 2016 run, when he gave eventual nominee Hillary Clinton a tougher fight than originally expected. This year, as voters get to know the crowded presidential field better, other candidates are eating into his support, Marsh said.

“The biggest threat to Bernie Sanders right now is Elizabeth Warren, and you can see that in the polling,” Marsh told the Washington Examiner.

In addition to inching up above Sanders nationally in the Economist/YouGov poll, Warren leads Sanders in key early state polls.