Federal agencies should implement mass layoffs of their workforces if the government shuts down next week, the White House told agencies on Wednesday, dramatically escalating the stakes of a potential funding lapse.

Democrats decried the proposed layoffs as an empty threat that they argue would backfire on Republicans rather than the minority party.

Democratic leaders said the administration’s plan to fire government workers in the event of a shutdown would not prompt them to drop their demands in their spending standoff with the G.O.P.