Lebanon's Western-backed prime minister rejected on Saturday opposition calls to step down and he vowed to continue his attempts to form a national unity Cabinet. For more than three weeks, Fuad Saniora has been trying to set up a Cabinet lineup acceptable to both the majority and the Hizbullah-led opposition. The formation of a national unity Cabinet is part of an Arab League-brokered agreement that ended Lebanon's long political stalemate that nearly plunged the country into a civil war. The Lebanese daily As-Safir, which is close to the opposition, reported Saturday that the opposition has issued Saniora with a 48-hour deadline to either form the Cabinet or step down. Legislator Ghassan Tueni, a member of the parliamentary majority, also urged Saniora to step down, saying the prime minister was unable to form a Cabinet amid political obstacles set up by rival factions. If Saniora fails to form a Cabinet by next Tuesday, Tueni said, "let him step down. This will be much better for him." But Saniora ignored the resignation calls, vowing to stay on until a new Cabinet is formed and described the opposition deadline as an attempt at "intimidation." "As long as the majority is determined to put its confidence in the prime minister-designate, this talk (of a deadline) is in vain," Saniora told reporters Saturday. Differences between the pro- and anti-government camps over the distribution of the four key sovereign ministerial portfolios - defense, interior, finance and foreign affairs - are holding up the formation of the new Cabinet. Christian opposition leader Michel Aoun, a key ally of Hizbullah, insists that one of the four key ministries - mainly the defense - should be allotted to his parliamentary bloc. This has been rejected by Saniora who said the defense and interior portfolios should be allotted to someone loyal to the president. On Saturday, Saniora repeated his offer to the opposition to choose either the finance or foreign affairs. The Doha deal calls for a 30-member national unity Cabinet in which Hizbullah and its opposition allies have veto power over government decisions. It also gives 16 Cabinet seats to the parliament majority, the opposition gets 11 seats and three remaining seats are to be distributed by the president.