Watch: White House briefs reporters as government shutdown threat looms

(The briefing is slated to start at 1:30 p.m. ET. Please check back if it doesn't appear right away.)

White House press secretary Sarah Sanders briefed reporters on Wednesday afternoon, as President Donald Trump prepared to meet with Republican senators to discuss his trade agenda.

Defense Secretary James Mattis was slated to join the briefing, too, as defense spending comes to the fore during a debate over the budget.

The briefing came during three days of tumultuous trading on Wall Street, during which the Dow Jones Industrial Average has swung wildly between positive and negative territory. As of midday Wednesday, the Dow was up more than 200 points for the day, or just shy of one percent.

Yet even as the markets seemed to recover somewhat from a massive sell-off Friday and Monday, a new threat to the U.S. economy lay on the horizon: A midnight Friday deadline to fund the government and avert another shutdown. if Congress fails to authorize a spending package.

House Republicans passed a short-term spending bill Tuesday night which has little chance of passing the Senate. On Wednesday, bother Republican and Democratic Senate leaders were to announce a tentative two-year deal to fund the government and boost both military budgets and non-defense spending.

This deal, however, will require the crafting of complex appropriations legislation, which could take weeks. In the meantime, it was unclear what kind of a short-term bill could pass both houses of Congress in order to mitigate the more immediate risk of a shutdown Friday.