Following Luis Lacalle Pou's narrow ballot victory tonight in counted votes, the Uruguayan electoral court is refusing to declare a winner in the election until the ballot envelopes set aside as "observed" are opened on Tuesday and the parties are given an opportunity to dispute the intention behind votes counted as anulled. With Luis's margin of victory just under the number of votes set aside as "observed", the Frente Amplio candidate theoretically has a chance to win if he seizes nearly all of the "observed" votes.
In the October election the Frente Amplio only won 30% of the "observed" ballots, a figure notably below the 39% in normal balloting when they lost the legislature. Observed votes are typically cast by disabled older, conservative voters requiring assistance to place their voting sheet in their balloting envelope.
The observed votes are further dwarfed by votes determined to be blank or anulled during the initial count leaving the possibility Uruguay gets to experience the extended uncertainty that gripped the US during the 2000 "hanging chad" controvery. In several circuits there were complaints of voting sheets for Luis Lacalle Pou's National Party in several circuits having been discretely marked in ways that would lead them to being anulled under Uruguay's strict anti-vote buying rules (archived).
By all measures Luis Lacalle Pou appears to have won the Presidential election today and counting observed and disputably anulled ballots should serve only to increase his margin of victory, but the space exists for Uruguay's left to steal the Presidency. Frente Amplio candidate Daniel Martínez just now got on stage and refused to concede the Presidential race to Luis Lacalle Pou's superior number of votes.