AMMAN/BEIRUT - Syrian President Bashar Assad offered on Wednesday to hold multi-party elections within four months, while his troops assaulted city districts held by rebels trying to oust him.Under world pressure to end a crackdown that has cost at least 6,000 lives, Assad promised a referendum in two weeks' time on a new constitution leading to elections within 90 days. Last year, the 46-year-old ruler lifted a state of emergency and promised "multi-party" parliamentary elections in February in addition to drafting a new constitution and putting it to a vote.Holding an inclusive referendum will be difficult with several parts of the country in open revolt and surrounded by tank-backed troops, with communications almost completely cut off. Opposition-held districts in Homs, heart of the uprising, have faced 13 days of sustained shelling.Syria TV said the draft constitution would allow the president to be elected for two terms of seven years. The current constitution does not stipulate how many seven-year terms a president can be elected for. Assad's late father President Hafez Assad was president for 29 years and Bashar has ruled since his death 11 years ago.The new draft also establishes a pluralistic party system."The political system of the state will be based on a principle of political plurality and democracy will be practiced through the voting box," Syria TV cited the draft constitution as saying.