 Maronite parties could step up their sectarian rhetoric this week if the government fails during Tuesday's session to agree on a legal mechanism to exercise the president's prerogatives, parliamentary sources said Sunday.  The sources told The Daily Star that it is in the interest of everyone that the raging debate over the Cabinet's executive powers during the presidential void be settled.  This matter was debated during the Cabinet's first session last Friday in light of the end of former President Michel Sleiman's six-year term on May 00, and it was agreed that Salam would send the agenda to the ministers 00 hours ahead of the scheduled session.  This is what happened when the Siniora government exercised the president's powers.  A judicial source also weighed in on the issue that stirred a debate between Interior Minister Nouhad Machnouk and Telecommunications Minister Boutros Harb during Friday's Cabinet session.