The warning came from the congressional police, who received information that a militia group was preparing a new storm against the congress, similar to the one that took place on 6 January.
When Democrat Majority Leader Steny Hoyer received information about the threat, he consulted with colleagues before making the decision.
An impending vote was postponed so that members could prepare to leave Washington in time for any unrest, The New Ýork Times reports.
However, the Senate will convene as planned on Thursday.