House Democratic leaders are urging their members to oppose the stopgap spending bill Republicans plan to bring to the floor on Tuesday, according to aides and lawmakers. This raises the likelihood that the government could shut down on March 14.

Republicans in the House released a stopgap spending plan over the weekend that would delay a government shutdown for at least six months, but it's unclear if they have the votes to pass the measure.

House Republicans unveiled a spending bill Saturday that would keep federal agencies funded through Sept. 30, pushing ahead with a go-it-alone strategy that seems certain to spark a major confrontation with Democrats over the contours of government spending.