MOSCOW, Oct 2 (Reuters) - Georgians go to the polls on Saturday to vote in local elections that could escalate a political standoff between the ruling party and the opposition a day after the arrest of ex-president and opposition politician Mikheil Saakashvili. Saakashvili, who left Georgia in 2013 and was sentenced to prison in absentia in 2018, was arrested on Friday after he returned to Georgia and called on his supporters to vote for the opposition and stage a post-election street protest. read more Georgia"s authorities had warned he would be arrested if he returned and President Salome Zourabichvili said that she would not pardon the 53-year-old after his arrest and accused him of deliberately trying to destabilise the country. The elections, which include a vote for the mayor of capital Tbilisi, have taken on significance amid a months-long political crisis that erupted in the wake of last year"s parliamentary election, which prompted the opposition to boycott the chamber. The head of the main opposition party, the United National Movement (UNM) that Saakashvili founded, was arrested in February and released in May amid a push by the European Union to broker a deal to ease the standoff between the government and the party. That deal collapsed over the summer when the ruling Georgian Dream party withdrew. The deal had said that Georgian Dream would need to call snap parliamentary elections if it failed to garner 43% of the vote at Saturday"s local elections. A recent poll showed popular support for Georgian Dream at 36%, below that threshold. Though the deal has now unravelled, political analysts said the vote could trigger protests if the ruling party fails to reach the threshold outlined in the deal and declines to call snap parliamentary elections. "If Georgian Dream doesn"t get what it got in the previous parliamentary elections, which was 48.22%, we might have some turmoil again, probably another wave of political crisis," said Soso Dzamukashvili, junior researcher at Emerging Europe. The return and arrest of Saakashvili on Friday has thrown in another wild card in the country of less than four million people. Before he was detained and placed in a detention facility, Saakashvili told his supporters to vote for UNM or for any small party that opposes Georgian Dream and to gather in central Tbilisi on Sunday. "Everyone must go to the polls and vote, and on Oct. 3 we must fill Freedom Square. If there are 100,000 people, no one can defeat us," he said.