President Donald Trump is emphasizing his vow to build a wall at the U.S.-Mexico border and additional conditions for an immigration deal, as congressional leaders and White House officials plan a meeting Wednesday that will set terms for a coming debate on the issue.

GOP lawmakers have largely avoided talking about the border wall, a central Trump campaign promise, in negotiations with Democrats on legislation to provide protection against deportation for 800,000 young undocumented immigrants while also bolstering border security and interior enforcement of immigration laws.

House Majority Whip Steve Scalise, a Louisiana Republican, said the wall remains part of the discussion. He told Fox News Tuesday, "There is an agreement that can be reached. It's got to start with border security, though, and putting money in place to start building the wall as President Trump said. He campaigned on this and he won the presidency with this being a front and center issue."

The president said in September that he would end the Obama-era program known as Deferred Action for Childhood Arrivals, or DACA, in early March. Trump has expanded his demands for what he wants in exchange for a DACA accord: Eliminating family immigration preferences and ending a diversity lottery program that provides visas to people in countries with low rates of migration to the U.S.

Trump punctuated the holidays with a series of tweets renewing demands that an immigration measure include a border wall, which is strongly opposed by Democrats and many Republicans in Congress. He's also accusing Democrats of playing politics in the debate.

"The Democrats have been told, and fully understand, that there can be no DACA without the desperately needed WALL at the Southern Border and an END to the horrible Chain Migration & ridiculous Lottery System of Immigration etc.," Trump said in a tweet Friday from his Mar-a-Lago club in Palm Beach, Florida.

He wrote on Tuesday, "Democrats are doing nothing for DACA - just interested in politics."

Immigration is one of the top issues that Congress pushed into 2018 as Republicans who control the Senate and House focused instead on passing a massive $1.5 trillion tax-cut measure. Democrats are insisting that the next federal spending bill include protections for the undocumented immigrants who were brought to the U.S. as children. The White House meeting Wednesday will include White House budget director Mick Mulvaney and legislative liaison Marc Short.

Trump isn't alone in seeking policies that could complicate the debate. Some GOP lawmakers are pushing for a mandatory "E-Verify" system for employers to ensure their workers are documented and to include deep cuts to legal immigration. Democrats insist Trump has promised he would support not only DACA protections but the "Dream Act" that provides the young immigrants a pathway to citizenship.

The DACA expiration puts pressure on all sides to act. Some of the young immigrants have expulsion protections that expire before March, with more than 7,900 already losing DACA protections since Trump acted in September, according to the Center for American Progress in Washington, a liberal research group. That number will rise to about 22,000 people by early March, the group said.

Bipartisan talks in the Senate for an immigration compromise, led by Democrat Richard Durbin of Illinois and Republican Lindsey Graham of South Carolina, could yield comprehensive immigration legislation as early as this month. Senate Majority Leader Mitch McConnell of Kentucky has pledged to put such a plan on the Senate floor this month if it has broad support in both parties.

Even if senators can reach accord, there will be risks in the House, where more Republicans are balking at the deportation protections. The last effort to enact a comprehensive immigration overhaul failed in 2013, when the Senate — then controlled by Democrats — voted to create a path to legal status for 11 million undocumented immigrants in the U.S. and to spend $46 billion to secure the U.S.-Mexican border. The Republican-dominated House didn't take up the bill, as most in the party opposed legal status.

Trump's support for any emerging compromise involving DACA could give political cover to some House Republicans from GOP-stronghold districts, but the ideological divide over the issue runs deep in that chamber. GOP Representative Steve King of Iowa continues to oppose any protection for people who are in the U.S. illegally. Some members of the conservative Freedom Caucus, including Representative Dave Brat of Virginia, have also expressed reservations.

Yet with 2018 midterm elections looming, a measure that addresses the needs of immigrants could benefit vulnerable GOP House lawmakers from districts with heavy concentrations of Latino voters. That includes Mike Coffman of Colorado, Darrell Issa of California and Carlos Curbelo of Florida.

"On this immigration issue, it's the extremists on both sides that have prevented a compromise and a solution for years," Curbelo said in an MSNBC interview last month. "People on the far right who call this amnesty, even though it's not, the people on the far left who believe this issue is so potent politically that they don't want it to get solved."

Meanwhile, a key issue splitting both political parties is how to enact any immigration compromise that might be reached. Democrats in both chambers are pushing to include it in the next federal spending bill, which must clear by Jan. 19 or risk a government shutdown. McConnell and other GOP leaders insist that it should move through Congress on its own.

House Minority Leader Nancy Pelosi, a California Democrat, made clear in a letter Tuesday to House Democrats that she'll reiterate her party's demand at the Wednesday meeting, which will also include discussion of spending and budget caps.

"We are firmly committed to swiftly passing the DREAM Act, which we know would pass with bipartisan support if brought to the floor," she wrote.

House Speaker Paul Ryan of Wisconsin said last month that Trump's deadline for DACA isn't until March and that there are other more pressing issues to deal with first. He has repeatedly said that DACA is "a separate issue" that shouldn't be lumped together with the discussion on government spending and extending other programs.