Mexico's Federal Electoral Institute, known as the IFE, on Wednesday began its official final vote count in an effort to determine who won Sunday's presidential election. Outside IFE's headquarters in Mexico City supporters of leftist candidate Andres Manuel Lopez Obrador are condemning the electoral body and threatening violence if the final result does not favor their candidate.

The demonstrators chant, "If there is no solution, there will be revolution."

They carry banners and signs, some supporting candidate Andres Manuel Lopez , others condemning the electoral institute and its president, Luis Carlos Ugalde. They accuse Ugalde of trying to perpetrate a fraud to steal the election from Lopez Obrador and hand it to ruling party candidate Felipe Calderon.

As police kept a wary watch, the numbers of protesters grew, from around 30 at the beginning of the day, to around 300 by mid afternoon. Elsewhere in the city, all appeared normal and there were few signs of discontent. Most Mexicans say they are willing to wait for the IFE to make its final count.

But if that count shows Calderon as victor, Lopez Obrador has promised to carry his fight to the electoral tribunal, which could take until September 6 to pronounce a winner. In the meantime, Lopez Obrador and his supporters are likely to continue marches and protests based on his claim that he won the election.

The preliminary count showed Calderon in the lead by about one percent, but IFE officials are examining around two-and-a-half million votes that were set aside for various inconsistencies. When the result of those votes is figured in, Calderon's lead dropped to around six tenths of one percent. Lopez Obrador and his supporters say there were many other irregularities as a basis for the legal challenges to come.

Most independent observers say Sunday's election went very well and that there were few serious irregularities reported. Calderon and his supporters say the vote count shows he won and that Lopez Obrador has failed to produce any hard evidence to challenge that result.

Lopez Obrador had claimed that the vote boxes set aside because of inconsistencies were "lost." But IFE officials note that his own party representatives were on hand for the entire process and knew where these votes were. They also say the rules by which questionable votes are set aside temporarily were agreed upon by all the political parties well in advance of the election.

Behind the dispute is Mexico's experience with corrupt and fraudulent elections during the 71 years of uninterrupted rule by one party, which ended when current President Vicente Fox won the 2000 election. While most Mexicans say they trust the independent and transparent electoral institute, which has run the past three national elections, many leftists and representatives of small farm and worker groups say they have no confidence in the system.

Political analysts note that whoever finally emerges as the winner of the election will have to govern a country deeply divided along ideological lines, where no one party has the votes in Congress to pass legislation and where distrust and anger over the election could undermine any chance of reconciliation.