President Donald Trump and Democratic lawmakers are in a standoff over funding the government, and the main sticking point is Trump's demand for $5 billion to build a wall along the U.S.-Mexico border.
Trump said during the campaign he was going to make Mexico pay for the barrier — but now he's asking U.S. taxpayers to fund construction. If there's no agreement, a partial government shutdown begins at midnight Friday.
Press secretary Sarah Huckabee Sanders signaled on Tuesday that Trump may be willing to work with Congress to avert a shutdown.
Here's a look at the status of wall.
IS IT A WALL OR A FENCE?
In Washington, it depends on who you ask. The president, seeking to show progress on one of his signature campaign promises, has repeatedly said he's begun construction on the wall with smaller amounts of money that Congress approved for border security. The Democrats, seeking to prove they haven't caved to Trump, say they would only fund improvements to border security that include fencing.
Customs and Border Protection Commissioner Kevin McAleenan called it a "border wall system" with Mexico that would include natural barriers and steel fencing that agents can see through.
Trump tweeted late Tuesday that his administration was building "artistically designed steel slats, so that you can easily see through it."
The March funding bill, passed with support from both parties, funded construction that greatly resembles some form of wall.
It included $641 million for 33 miles of construction in South Texas' Rio Grande Valley, the busiest area for illegal crossings. In one section, U.S. Customs and Border Protection wants to install 18-foot-tall bollards with narrow spacing between each post.
According to an online solicitation, the agency plans to install the bollards atop "a concrete wall to the approximate height of the levee crest." In some places, the wall and the bollards would exceed 30 feet.
Contracts have been awarded to build some 33 miles (53 kilometers) of wall in the Rio Grande Valley. Construction is scheduled to start in February. A federal judge last week ordered two hold-out landowners to allow surveyors onto their property after the government took them to court.
WHAT IS ALREADY CONSTRUCTED?
Overall some type of barrier runs along about 685 miles (1,046 kilometers) of the 1,954-mile (3,126-kilometer) border.
But 654 miles (1,052 kilometers) came before Trump took office, constructed under the Secure Fence Act during the Bush administration.
As Republicans have since pointed out, a majority of Democrats in the Senate voted for the act, including then-Sens. Hillary Clinton and Barack Obama.
In budget year 2017, Congress provided $292 million to the U.S. Department of Homeland Security to build a steel-bollard wall to replace "ineffective" barrier in Southern California, New Mexico and far West Texas.
More than 31 of 40 miles have been constructed, and nine remaining miles are scheduled to be completed by 2019. Construction began on 4 miles (6 kilometers) in far West Texas and New Mexico, and 14 miles (22.4 kilometers) of replacement in San Diego should be done by May 2019.
Several groups have filed lawsuits challenging the administration's waivers of environmental laws to build more quickly.
The Department of Homeland Security has used authority received in 2005 to bypass reviews and regulations of border wall construction under the Endangered Species Act, the Clean Water Act, and two dozen other laws.
In several places, planned construction would cut through protected areas or habitat for endangered species. One conservation-related legal challenge was heard on Tuesday in federal court in Washington. The groups argue the project in New Mexico would displace rare wildlife, including the aplomado falcon and Mexican gray wolf.
In South Texas, almost 70 percent of the land at the National Butterfly Center, which provides habitat to migrating species, including monarchs, would be cut off by the planned barrier. The nonprofit that operates the butterfly center has also sued.
So far, no judge has stopped the government from moving forward.
WHAT WOULD THE GOVERNMENT DO WITH THAT $5 BILLION?
Homeland Security officials said they would combine previous funding to construct 330 miles of a "border-wall system" along the Mexican border, including 104 miles in the Rio Grande Valley.
Sanders said on Fox News on Tuesday there are "other ways that we can get to that $5 billion," including one bill she says would provide $26 billion in border security, including $1.6 billion for the wall.
Sanders did not deny that the White House was exploring a way to use Defense Department funds for the remaining cost of the wall.
She said there were "a number of different funding sources" that could be used, and she expected they could find a legal way to use defense money.
Trump administration officials have been discussing the possibility of using Defense Department funding as a way around a shut down, but there are legal and congressional hurdles.
She said: "At the end of the day, we don't want to shut down the government. We want to shut down the border from illegal immigration."