President Donald Trump boards Marine One to return to the White House after receiving treatments for covid-19 at Walter Reed National Military Medical Center, Monday, Oct. 5, 2020, in Bethesda, Md.

Stocks turned sharply lower on Wall Street Tuesday afternoon after President Donald Trump ordered a stop to negotiations with Democrats on a coronavirus economic stimulus bill until after the election.

The S&P index slid 1.3% after Trump tweeted his mandate. The benchmark index had been up 0.7% just prior to the president's announcement with about an hour of trading left.

In a series of tweets about the negotiations between the White House and Speaker Nancy Pelosi, Trump said: “I have instructed my representatives to stop negotiating until after the election when, immediately after I win, we will pass a major stimulus bill that focuses on hardworking Americans and small business.” He also accused Pelosi of not negotiating in good faith.

The comments from the president came just hours after Federal Reserve Chair Jerome Powell urged Congress to come through with more aid, saying that too little support “would lead to a weak recovery, creating unnecessary hardship for households and businesses.”

Trump's announcement dashes Wall Street's hopes that another round of stimulus for the economy, which has been punched into a recession by shutdowns related to the coronavirus pandemic, could soon be on the way. Bitter partisanship on Capitol Hill has been preventing a compromise on more aid. Reports on the economy have been mixed recently, as some areas show a slowdown after extra unemployment benefits and other stimulus earlier approved by Congress expired.

AP Business Writer Elaine Kurtenbach contributed.