WASHINGTON — Congress has until Friday to reach an agreement on a thicket of thorny issues, and the talks don't appear to be going very smoothly right now.

That means President Trump and lawmakers on Capitol Hill are hurtling toward a government shutdown, with funding set to run out at midnight on Jan. 19.

Here's a look at the four key obstacles lawmakers face in their efforts to forge a deal by Friday.

Spending caps

Lawmakers are currently faced with tight budget caps, agreed to in 2011, that limit how much they can spend for the rest of fiscal year 2018 and beyond.

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Both Republicans and Democrats want to lift those caps — GOP leaders want a big boost for defense; Democrats say any defense increase should be paired with an equal hike for domestic programs.

House and Senate leaders have been negotiating for weeks over how much to increase the caps and how to divide the pot between defense and domestic spending. They insist the talks are going well, while offering no details.

"We think the solution is in sight," House Minority Leader Nancy Pelosi, D-Calif., told reporters on Thursday.

House Speaker Paul Ryan, R-Wis., offered a similarly rosy assessment. But he noted that once they have settled on a top-line number, lawmakers on the appropriations committees in the House and Senate will need time to craft a spending bill that sets specific funding levels for every government agency and program.

In other words, Congress will almost certainly have to pass another short-term measure before Jan. 19 to buy themselves more time. Whether such a stop-gap funding bill could pass is unclear; opposition to a short-term deal is bubbling up from conservatives and liberals alike.

The Dreamers

The partisan debate over how to deal with the Dreamers — the 800,000 immigrants who were brought to the U.S. illegally as children — grew more acrimonious last week after President Trump allegedly called Haiti, El Salvador, and other African nations "s__hole countries" and suggested the U.S. should instead encourage more immigration from Norway, a predominately white country.