WASHINGTON (Reuters) - As the partial U.S. government shutdown entered its 17th day, no clear end was in sight, with Republican President Donald Trump and congressional Democrats in a standoff over his demand for $5 billion for a U.S.-Mexico border wall.

The U.S. Capitol building is seen as a partial government shutdown continues in Washington, U.S., January 7, 2019. REUTERS/Jim Young

It is hard to see how the impasse will be resolved but here are some possible scenarios for how it might play out, as well as potential winners and losers, based on interviews with lawmakers and aides in Congress and the Trump administration.

A COMPROMISE EMERGES

As the closure of a quarter of the government begins to hurt the economy, both sides could give ground and do a deal, possibly based on the following factors.

* “Dreamers.” These mostly young Latin Americans are living in the United States after being brought into the country illegally as children. Trump could offer to protect them from deportation in return for wall money. A deal along these lines was nearly achieved previously but collapsed.

* Barrier, not wall. Trump has insisted on funding for a “wall” but he has also talked about steel fencing. Tall, slatted fences already are in place in some spots on the border and more are being built. Funding for more slats could let Trump declare victory and let Democrats say they blocked a wall. The same could be said for steel mesh pedestrian barriers and other types of fencing.

* Other steps. There are many additional ways to fortify the U.S.-Mexico border, such as deploying more all-terrain vehicles and border guards on horses. Large metal detectors also could be installed to scan trucks and buses for illegal activities.

* Follow the money. A dollar-figure bargain could be reached somewhere between Trump’s demand for $5 billion in wall funding and the Democrats’ offer of $1.6 billion for border security.

TRUMP DECLARES ‘NATIONAL EMERGENCY’

Trump has threatened to declare a national emergency, claiming that illegal immigration jeopardizes U.S. security and empowers him to redirect existing federal funds to build his wall, perhaps by tapping the Defense Department budget. Under the Constitution, Congress holds the power to make decisions about spending U.S. taxpayers’ money. Such a step by Trump would escalate what is now a policy dispute into a fight over presidential powers. Democrats would almost certainly move to block Trump, likely kicking off a protracted court battle.

DEMOCRATS FOLD, TRUMP WINS

Democratic leaders Nancy Pelosi and Chuck Schumer have vowed they will not give Trump any money to build a wall but as the shutdown grinds on, they could have second thoughts, although this seems unlikely given the political climate.

Democrats won a majority in the House of Representatives by a landslide in November’s elections. Trump’s approval rating continues to hover at around 40 percent. There is plenty of skepticism among voters about the need for a wall, polls show.

In addition, more voters blame Trump for the shutdown than congressional Democrats, a Reuters/Ipsos poll found in late December.

TRUMP BACKS DOWN, DEMOCRATS WIN

Trump, whose main responsibility as president is to make sure that the federal government carries out its duties, could find the shutdown too politically hazardous as everyday problems increasingly confront average Americans.

Closed national parks and museums is one thing. But federal airport security screeners, now working without pay, have begun calling in sick, potentially causing delays for air travelers.

Trump has promised for years to build his wall - initially saying Mexico would pay for it - and has repeatedly attacked Democrats for standing in his way. Now he may find the shutdown unsustainable, fold and endorse Democrats’ shutdown-ending bills while finding a way to claim victory.

Bills passed by the House last week would fund the Department of Homeland Security through Feb. 8, giving the White House and Congress more time to negotiate on border security. Other agencies, such as Agriculture, Justice and Commerce, would have their funding restored under separate legislation.

Democrats this week plan to start passing agency-by-agency funding bills in the House of Representatives that they would then send to the Senate. Republicans there would then have to decide whether to approve the bills or block them in the name of Trump’s wall project. Blocking a bill to fund the Treasury Department, for example, might delay Americans’ tax refunds.