VILLAHERMOSA, Mexico — The newly elected governor of Tabasco state was sworn in Saturday while 3,000 protesters in the capital's central square demanded new elections.
Hundreds of riot police guarded government buildings, but no clashes were reported.
The demonstrators, mainly peasants, claim Roberto Madrazo Pintado of the ruling Institutional Revolutionary Party (PRI) won the Nov. 20 election through fraud and voter intimidation.
Madrazo has denied the charges, noting that independent election monitors, new campaign financing laws and other recent reforms guaranteed a fair vote in this Gulf Coast state.
In a speech after his swearing-in, Madrazo, 42, promised an honest administration, judicial and educational reforms, social justice and dialogue with his opposition.
The protesters support Andres Lopez Obrador of the leftist Democratic Revolutionary Party, who got 38% of the vote to Madrazo's 54%.
Lopez Obrador had vowed to prevent Madrazo from entering the government palace and suggested he might set up a parallel government such as the one in neighboring Chiapas state, where Gov. Eduardo Robledo Rincon faces a similar challenge.
Rincon, also of the ruling party, attended Madrazo's inauguration. But in a surprise move announced just days earlier, President Ernesto Zedillo canceled and sent no official representative.
Thousands in Tabasco are angry over problems including pollution of fisheries and farmland by the government oil monopoly and low prices for the principal crops of coconut and cacao.