MEXICO CITY, Oct 17 (Reuters) - Mexico"s national election authority said Sunday that 2.85 million signatures are necessary to move forward with a recall referendum on President Andres Manuel Lopez Obrador"s mandate. The National Electoral Institute (INE) said 3% of the 94,845,915 registered voters in 32 states would need to show support between Nov. 1 and Dec. 15, mainly through its mobile app, in order for the recall referendum to move forward. Lopez Obrador, who took office in 2018, has long said he would hold a recall referendum halfway through his term to decide if he continues in office. Opposition parties, however, are against the referendum, which they see as a way to polarize voters and galvanize supporters of the president, who has consistently enjoyed support of around 60%.