Sen. Bernie Sanders is prepping for a second Democratic presidential bid.

The Vermont independent, who caucuses with Senate Democrats, has recorded a campaign video declaring his candidacy, Politico reported. That strongly suggests the socialist is set for a repeat White House bid after falling short in 2016 to eventual nominee Hillary Rodham Clinton.

The timing for the release of the Sanders campaign video is unclear.

Whenever it is, though, Sanders is likely to find the left flank of the Democratic primary field crowded territory. Sen. Elizabeth Warren of Massachusetts is wooing progressives with a universal wealth tax. Sen. Kamala Harris of California is pledging a government-financed health system, at one point even calling for an end to private health insurance. And Sen. Sherrod Brown of Ohio, a longtime favorite of organized labor, is considering a presidential bid in 2020.

Sanders, 77, in 2016 won the hearts of many young voters and exposed weaknesses in Clinton's campaign. While she ultimately captured the Democratic nomination, Sanders won several small-population state caucuses and the Michigan primary — presaging Clinton's loss there in November to Republican nominee Donald Trump.