Negotiations on border security funding are underway in Congress as the threat of another government shutdown looms large over Capitol Hill.

But President Donald Trump, who has made it his key goal to secure funding toward a southern border barrier, appeared to be more pessimistic than ever about the outcome of the talks.

"Republicans on the Homeland Security Committee are wasting their time," Trump said in a tweet Thursday morning. "Democrats, despite all of the evidence, proof and Caravans coming, are not going to give money to build the DESPERATELY needed WALL."

"Wall is already being built, I don't expect much help!" he added.

Trump tweet

The dismissive statement appeared to reference a bipartisan conference of 17 lawmakers in the House and Senate tasked with hashing out a deal to fund the government.

The White House did not immediately respond to a request for clarification on the president's tweet.

The pressure's on for the group of lawmakers, with about two weeks remaining on a self-imposed deadline before parts of the government once again shut down. Politicians on both sides of the aisle have made it clear they want to avoid at all costs another government funding lapse, especially so soon after the record-shattering 35-day partial shutdown.

Trump is demanding that any long-term funding deal include billions of dollars toward the construction of a barrier along the U.S.-Mexico border. Democrats have refused to put any money toward a wall, and have accused Trump, who once said he would be "proud" to shut down the government in pursuit of a wall, of holding federal workers hostage to gain leverage in the debate.

Trump on Friday signed a temporary measure to reopen the full government for three weeks. The move came after a slew of polls showing more Americans blamed him for the shutdown than blamed Democrats.

But he maintained after the bill signing that any deal must include new border wall funding — and renewed his threat to bypass Congress all together by declaring a national emergency if he doesn't get what he wants.

"In 21 days, if no deal is done, it's off to the races!" Trump tweeted at the time.

Trump tweet off to the races

In another tweet Thursday, Trump called for a return to describing his plan as a "WALL," appearing to abandon other variations.

As a presidential candidate, Trump repeatedly and nearly exclusively referred to a wall along the border. Ahead of the shutdown debate, however, Trump began calling the proposal a "steel barrier" or "artistically designed steel slats."

trump tweet artistically designed steel slats

Trump tweet steel slats drawing

At the White House on Jan. 4, Trump said, "I think we're probably talking about steel because I really feel the other side feels better about it." In his first televised Oval Office address, Trump claimed, "At the request of Democrats, it will be a steel barrier rather than a concrete wall."

But Trump tweeted Thursday: "Lets just call them WALLS from now on and stop playing political games! A WALL is a WALL!"

Trump tweet WALL is a WALL