CARACAS, Jan 22 (Reuters) - Some supporters of an effort to remove Venezuelan President Nicolas Maduro from office through a referendum said on Saturday they would ask the country"s top tribunal to review signature collection conditions set by the electoral commission. The national electoral commission said earlier this week that three opposition groups had requested a recall vote against Maduro, which would need 4.2 million signatures of support to go ahead. Venezuela"s constitution allows officials who have completed at least half their term to be removed from office by a vote. Maduro completed the first three years of his second term earlier this month. The commission - whose five-member board includes three people connected to the ruling party - said late on Friday signatures supporting the referendum can be collected during just 12 hours on Jan. 26 at only 1,200 locations. Two opposition figures - Nicmer Evans and Cesar Perez Vivas - sent a request by email for the country"s Supreme Tribunal asking it to review the commission"s decision and said in an online news conference they would use all legal means to get the referendum. "You would have to process five voters per minute for 12 hours," to reach the signature threshold under the rules, commission member Roberto Picon, who is close to the opposition, said on Twitter late Friday. "It"s not feasible." Pollsters say seven of every 10 Venezuelans would support a change in government, as the country"s economic and social collapse grinds on.