Federal funding expires at midnight on Friday, April 28, which is technically Saturday, April 29 —Trump's 100th day in office. In order for the government to continue operating, both chambers of Congress and the White House need to approve an appropriations bill, or a spending bill.
Although negotiations have been in the works for weeks, there are disagreements among the different parties about the final draft. The White House, for instance, is publicly advocating for funds for a border wall with Mexico, which Congressional Democrats, and even some Republicans, oppose. Trump signaled Monday night that he could back off that demand. Senate Republicans, of which there are only 52, may need 60 votes to advance the spending bill in their chamber if Democrats filibuster. And if no bill passes the Senate in time, Trump won't have anything to approve.
A shutdown last happened in October of 2013, during former President Obama's Administration. Clashes between a Republican-controlled Congress and a Democratic White House were blamed as the catalyst for the shutdown, which lasted 16 days.
Here's what you need to know about a government shutdown.
What actually happens during a government shutdown?
If no spending bill is approved before the deadline, the federal government will be forced to shut down. Contrary to the name, however, this doesn't mean all of the government just goes into hibernation.
In 2013, for instance, some crucial aspects of the government, like the military and the State Department, stayed fully functional, according to a CNN analysis of the shutdown.
But other portions of the government, like national parks, zoos and museums, all of which are federally funded, ceased operations entirely. So did sectors more pertinent to governance, such as the Office of Government Ethics and the Federal Communications Commission. Others, such as the Departments of Education, Defense, Commerce and Homeland Security, remained partially opened.
Federal employees who work in the sectors of the government that cease operation are "furloughed," during a shutdown, or given a leave of absence without pay.
A shutdown is also costly. The 2013 shutdown, according to a report from the Office of Management and Budget, cost the government $2 billion, and the Council of Economic Advisers estimated it reduced the creation of private sector jobs by $120,000.
Are there temporary solutions to avoid a shutdown?
Yes. Its entirely possible that Congress and the White House won't be able to agree on a bill, but the government stays open. Congress can pass a continuing resolution, a short term spending bill that keeps the government open while agreements are still being worked out. That could be for as little as a week.
What do voters think about shutdowns?
Voters are generally not supportive of government shutdowns. A Politico-Morning Consult poll from early April around that 65% of registered voters thought Congress should "take all necessary steps to avoid a government shutdown," while only 17% thought it would be OK to "if it helps them achieve their policy goals." An Economist Group/YouGov poll in April found 60% of Americans preferred keeping the government open while only 19% wanted a shutdown fight over border wall funding.
Those numbers are consistent with past shutdowns. A Washington Post-ABC News poll after the 2013 shutdown found that 81% of Americans disapproved, including two-thirds of Republicans and independents who lean Republican, as well as a majority of those who supported the Tea Party movement. And a Washington Post-ABC News poll during a similar shutdown fight in 1995 found that 72% of thought shutdowns should not be used as a tool in budget negotiations.