Senegal's President Abdoulaye Wade has dropped some of his planned constitutional changes, officials say.He no longer wants to reduce the proportion of votes needed to win a presidential election, and avoid a run-off, from more than 50% to 25%.As MPs met in the capital, Dakar, to discuss the planned amendments, riot police used tear gas and water cannon against demonstrators outside.The bill also creates the elected position of a vice-president.Government spokesmen Serigne Mbacke Ndiaye said Mr Wade had abandoned the idea of reducing the threshold to win a presidential election to 25%, Reuters news agency reports.According to the AFP news agency, Justice Minister Cheikh Tidiane Sy informed MPs about the decision.Clouds of tear gas hovered over the square in front of the National Assembly, where lawmakers had gathered on Thursday, AP news agency reports.Critics had said the run-off amendments were designed to ensure that Mr Wade, 85, was re-elected next year.Mr Wade first came to power in democratic polls more than a decade ago but he is now facing growing anger at daily electricity cuts and the rising cost of living.BBC West Africa correspondent Thomas Fessy says many people also fear that Mr Wade intends to give the role of vice-president to his son Karim, who is already a powerful minister in the current administration.They say Mr Wade could then step down and hand power to his son.The governments says the proposed new post is aimed at reinforcing democracy by sharing power between the president and vice-president.Riot police also clashed with protesters earlier this week, while world-famous Senegalese singer Youssou Ndour urged the government to "see sense".Source: BBC