Lome - Police in Togo fired tear gas to disperse thousands of opposition supporters who staged a sit-in late on Thursday urging the president to step down, as anger grows over the Gnassingbe family's 50 years in power.Opposition supporters dressed in orange and red were sitting in the capital's main square playing music, cooking and singing when police fired tear gas. The sit-in followed two days of demonstrations demanding the return of the West African nation's 1992 constitution, which includes presidential term limits.Internet service has been down in Togo during the protests.Parliament says it will vote on Tuesday on a draft bill that would return to that constitution, though it has not provided a copy of the draft or further details. Two years ago a similar bill was rejected in Parliament, where the ruling party holds a majority of seats.The opposition parties also are demanding that Togo's diaspora population of 2 million have the right to vote in the 2020 presidential elections.The opposition also seeks the resignation of President Faure Gnassingbe. While Gnassingbe has not said he will run again in 2020, the opposition National Panafrican Party has said it suspects he will not quit power unless compelled to step down.Gnassingbe took over in 2005 after the death of his father, Eyadema, who ruled for 38 years. Before his death, he modified the constitution to extend his rule. The constitution had allowed for only two five-year terms.Protests began in August, and security forces killed at least two people and injured several others, Amnesty International said. Dozens were sent to prison for up to 60 months, according to the human rights group.The government condemned the August protests, with the interior minister calling them extremist.Mohamed Ibn Chambas, the UN secretary-general's special representative for West Africa and the Sahel, met with the president and opposition parties on Thursday to urge dialogue."The president of the republic assured me of his good disposition to engage with all the stakeholders in a constructive way," he said in a statement.