As a partial U.S. government shutdown hit the two-week mark, President Donald Trump and congressional leaders prepared to meet today over ways to break an impasse pitting his demand for building a border wall against Democrats’ call for alternative security measures.

About 800,000 federal workers have been affected by the Dec. 22 closure of about one-quarter of the federal government as Trump withheld his support for new funding until he secures $5 billion to start building the wall along the U.S.-Mexico border that he promised during his campaign.

Such a wall, he has argued, is needed to stem the flow of illegal immigrants and drugs over the southwestern border. When he ran for president in 2016, he vowed Mexico would pay for the wall, which it has refused to do.

On Thursday, Trump tried to keep the pressure on Democrats, even as they gained significant new power with their takeover of the House of Representatives at the start of a new Congress.

“Build the Wall,” the Republican president demanded on Twitter. In remarks to reporters that same day, Trump said: You can call it a barrier. You can call it whatever you want. But essentially, we need protection in our country.”

As Trump dug in, so did opposition Democrats, leaving many to wonder just how much progress might be made during Friday’s White House meeting scheduled for 11:30 a.m.

Vice President Mike Pence, in a television interview Thursday night, also suggested that in exchange for the wall, the White House could work with Democrats on so-called Dreamer immigrants who were brought to the United States illegally as children; an idea Trump had rejected on Wednesday.

“It’s being talked about,” Pence told Fox News.

Democrats back other border security measures aside from the wall, and their two-bill package passed Thursday includes $1.3 billion for border fencing and $300 million for other border security items such as technology and cameras.

Without a deal to end the partial government shutdown, the Department of Homeland Security will not be able to bring some furloughed workers back to their jobs while others continue to be forced to work without paychecks for the time being.