(CNN) Republicans and Democrats will sit down with President Donald Trump in a bipartisan meeting Tuesday aimed at moving closer to protecting hundreds of thousands of immigrants from deportation, but a long-entrenched partisan divide over immigration policy and a looming budget deadline are threatening progress.

Republican and Democrats involved in negotiations over the must-pass January spending deal say that DACA -- the Deferred Action for Childhood Arrivals program -- has become the key to unlocking any funding agreement and some are frustrated with how negotiations are unfolding. Republicans charge that Democrats have all but halted talks on spending caps until there is a resolution on DACA, which gives undocumented immigrants who came to the country as children a chance to stay, work or study in the US without fear of deportation.

"Seems to me that Democrats are holding that deal hostage for a DACA negotiation and we are meeting at the White House tomorrow on a bipartisan basis with the President to see what that might look like," said the Senate's No. 2, Texas Republican John Cornyn. "But I think that's going to make the January 19 date pretty hard to hit."

"It's a mess," said one person directly involved in the negotiations.

A separate GOP aide said the broader environment for both parties simply "isn't in a good place right now."

Democrats argue the White House hasn't been fully engaged to the degree it needs to be and say that a long and broad policy wish list released last week just further irritated Democrats working closely on the immigration compromise. One Democratic aide argued the White House's list was "out of the realm of reality."

"No wall," said Democratic Sen. Kamala Harris of California. "Listen, I believe in border security. I think it's very important that we have a secure border, but spending billions and billions of dollars on this wall because of a political promise and a campaign promise is ridiculous."

What Tuesday's meeting means

The meeting at the White House on Tuesday was expected to -- at the very least -- symbolize that Trump was growing more serious about finding a bipartisan resolution. But adding more tension to the anticipated meeting for Democrats is the fact the White House invited GOP lawmakers Democrats view as openly hostile to finding a consensus deal on DACA.

In the background, details are still being worked out on what a plan to help recipients of DACA would look like, and a bipartisan group of Senate lawmakers led by Democrat Dick Durbin of Illinois and Republican Lindsey Graham of South Carolina continues to negotiate.

However, the tensions that existed in December but had been overcome with a holiday deadline are playing out in real time now between the two parties.

"I think this is going to be the flexion point where we get some things done or we don't," Rep. Adam Kinzinger, a Republican from Illinois, said Monday afternoon on CNN.

On Capitol Hill, bipartisan talks have been ongoing for months and the group of senators led by Durbin and Graham acknowledge they need Trump to lay out clear priorities to move forward.

The thinking is that Trump -- who secured the Republican Party's nomination by promising mass deportations and a border wall -- can offer political cover for Republicans who may be fearful of backing any immigration bill that is viewed as amnesty among their base. With Trump's blessing, Republicans believe they can find a way to move ahead on DACA. Without it, the votes are compromised.

The bipartisan meeting at the White House on Tuesday comes after Trump met with Republicans last week at the White House and Sen. Jeff Flake of Arizona refused to attend, citing the lack of bipartisanship.

White House chief of staff John Kelly, formerly the secretary of homeland security, will also be in the bipartisan meeting Tuesday and has been leading outreach to lawmakers on Capitol Hill on the ongoing talks.

Also on the list Tuesday are a host of lawmakers who would be expected, including Durbin and Democratic Sen. Bob Menendez of New Jersey, a 2013 immigration reform veteran. But the list also includes red state Democrats like Sens. Heidi Heitkamp of North Dakota and Jon Tester of Montana, as well as Democratic Rep. Henry Cuellar of Texas, who frequently votes with Republicans on immigration and border issues -- a sign that the White House is looking to pick off as many Democrats as it can even if it can't work with the party's key negotiators.

Flake told CNN he's prepared to tell Trump on Tuesday that this DACA deal cannot include a whole host of immigration policy changes but instead has to be narrowly focused if Republicans want to succeed.

"This is not a comprehensive reform bill," Flake said. "We can't do one before March."

More than one group pushing immigration plans

In addition to the bipartisan working group, conservatives including Cornyn and Senate Judiciary Chairman Chuck Grassley of Iowa are having their own conversations, and Republican Sens. Thom Tillis of North Carolina and James Lankford of Oklahoma are also going to be at the White House on Tuesday.

In the House, multiple efforts are underway as well, many led by rank-and-file members. Republican Rep. Will Hurd of Texas and Democratic Rep. Pete Aguilar of California have released their own bipartisan framework for a deal after weeks of negotiations. Aguilar is the whip for the Congressional Hispanic Caucus. That deal focuses on DACA and border security, but the lawmakers hope additional measures could be added if necessary to finalize a deal.

The bipartisan Problem Solvers Caucus -- including Republican Rep. Carlos Curbelo of Florida, a longtime DACA advocate -- had also been working to reach a compromise that before the break was similar in concept to what the Senate group was working on.

And, as in the Senate, a group of more conservative Republican lawmakers are working on their own proposal, including House Homeland Security Chairman Mike McCaul of Texas and House Judiciary Chairman Bob Goodlatte of Virginia, which would be strongly to the right of most of the bipartisan compromises. Both men will also be at the White House on Tuesday.