US stocks had their worst day in eight months on Wednesday as investors wrestled with anxieties over how Washington politics could derail the Trump rally.

The recent turmoil over revelations that President Trump allegedly tried to pressure former FBI Director James Comey to drop his probe into ex-National Security Adviser Mike Flynn could bog down the president’s plans to stimulate the economy, many fear.

With those fears now in many investors’ heads, the Dow Jones industrial average tumbled 372 points, or 1.8 percent, on Wednesday, 20,606.93. It was the biggest one-day slide since Sept. 9, when the market was spooked by fears of an unexpected rise in interest rates.

The S&P 500, a broader stock measure, also slid 1.8 percent, to 2,357.03. The Nasdaq, which hit an all-time high on Tuesday, fell 2.6 percent, to 6,011.23.

President Trump has hoped to pass his economic agenda this year — including tax cuts, public works spending and a regulation rollbacks — but that may now be impossible with Congress wrapped up in the Comey controversy.

“If Trump stays in office, then it impedes the progress of tax reform,” Sam Stovall, market strategist at CFRA, told The Post.

On Wednesday, investors were spooked, for once, by the lack of tweets coming from Trump’s Twitter streams. In the past, the president had used the platform to defend himself against stories he saw as unfair.

“I don’t know what that’s about. That looks a little interesting, doesn’t it? We’re always just one tweet away,” Chris Rupkey, chief financial officer at MUFG Union Bank, told The Post.

Market soothsayers were split on how deep a pullback could go — from 100 points in the Dow to a full-on correction of more than 10 percent, or 2,000 points.

Few were expecting markets to move much higher in the near term.

“Is the Trump trade over? I think doubts have crept in,” Josh Feinman, chief global economist at Deutsche Bank’s asset management arm, told The Post. “The political stumbles by the administration make it tough to get the agenda through, for sure. That agenda was having trouble already.