A storm of perjury charges, subpoenas and political gamesmanship blew up and down Pennsylvania Avenue on Thursday as congressional Democrats widened what had started as a probe into whether President Bush’s aides directed the firings of federal prosecutors.

Midway down the historic boulevard, Justice Department officials sought to explain congressional testimony by FBI Director Robert Mueller that — under protracted, hard-to-follow questioning — seemed to contradict the sworn comments of Attorney General Alberto Gonzales.