From our friends at Politico.com:
While it’s rare for Byrd to criticize a president in his own party, Byrd is a stern constitutional scholar who has always stood up for the legislative branch in its role in checking the power of the White House. Byrd no longer holds the powerful Appropriations chairmanship, so his criticism does not carry as much weight these days. Byrd repeatedly clashed with the Bush administration over executive power, and it appears that he’s not limiting his criticism to Republican administrations.