that is very much possible,a good example is the american presidential election,no matter how much the republicans kept selling the war and mcains experience the economy was the deciding factor in the end,our people too will tighten their belts to some extent for the sake of our country and for peace,but if they go on neglecting the economy as MR & Co. is doing right now,theoratically it won't be long before people will vote for a candidate or party with a better economic policy.I emphasize the word "theoratically" because the sri lanken voters are a very unpredicteble bunch.
As for your charismatic leader from the opposotion,I can think of one,but I won't mention his name because there were some contradicting posts on another thread regarding the actions of his parentage.