Washington, Jan 16 (IANS): US President Donald Trump has called tens of thousands of federal employees back to work without pay to get the government running amid a partial shutdown well into its third week.

Out of 800,000 federal workers who didn't receive paychecks during the shutdown, nearly 50,000 furloughed employees were called back to their jobs amid the crisis that was affecting dozens of federal agencies, the Washington Post reported.

A federal judge on Tuesday rejected a bid by unions representing air traffic controllers and other federal workers to force the government to pay them if they were required to work. The shutdown began on December 22.

The administration's move came as the White House and Congress made no progress towards resolving their underlying dispute. Democrats in the House have been pushing forward with bills to reopen the government, while Trump has been switching from one strategy to another to win $5.7 billion funding for his border wall with Mexico.

The President had earlier extended an unusual lunch invitation to a handful of rank-and-file House Democrats in an attempt to woo them and create a divide within the Democratic camp over the shutdown.

But the lawmakers rebuffed the outreach as Democratic leaders voiced concerns the meeting would prove little more than a photo opportunity bolstering the President.

Trump urged his supporters on Tuesday to voice support for the border wall. "We're going to win," he said.

"They're (federal workforce) not being paid right now because of the Democrats. People are impressed with how well government is working with the circumstances we're under," the president added.

Democrats have called on Trump to reopen the portions of the government that have nothing to do with the wall before they negotiate with him on that issue. But he has refused to pay heed to their calls.

Now, increasing numbers of Republicans are urging Trump to reopen the government, even if just on a short-term basis as negotiations continue.