President Donald Trump said that federal workers furloughed in a partial government shutdown support his effort to force Democrats to vote to spend billions of dollars for a wall on the Mexican border.

"They understand what's happening. They want border security," Trump told reporters at the White House on Tuesday, after he was asked what message he had for workers affected by the shutdown.

Nine of 15 federal departments and dozens of other agencies shut down on Saturday after Trump refused to sign a spending bill that didn't include money for the border wall, his top campaign promise. Hundreds of thousands of government employees have been put out of work by the dispute or are forced to do their jobs without pay.