(CNN) -- Mexican authorities were counting votes Monday in a high-profile state election involving President Felipe Calderon's sister.
Luisa Maria Calderon ran for governor in the state of Michoacan on the conservative National Action Party (PAN) ticket.
Preliminary results Monday morning showed her trailing behind Fausto Vallejo, the mayor of the state's capital, Morelia. With 100% of votes counted in the preliminary tally, Vallejo had won 35.3% of votes, while Calderon garnered 32.6%.
State elections officials said late Sunday that results were too close to call, and they announced that they expected to release final tallies Wednesday.
Vallejo, of the Institutional Revolutionary Party (PRI), declared victory several minutes after polls closed Sunday.
At the same time, Gustavo Madero, the PAN's national party president, told reporters three exit polls commissioned by the party showed a victory for Calderon.
The state elections come during tense political times in Mexico, where presidential campaigns for the 2012 elections are kicking into high gear. Some have said Michoacan elections may be viewed as a litmus test of the popularity of the president -- and the crackdown on drug cartels he started in his home state.
Analyst Eduardo Huchim told CNN en Español that the state elections in Michoacan are not directly connected with the presidential race, but he said the specter of insecurity and violence loomed large.
"The state has been very connected with the explosion in drug trafficking and the war against drug trafficking," he said.
Michoacan is ground zero in Mexico's drug war. Shortly after he took office in December 2006, President Calderon announced plans to deploy troops there.
Mexican authorities have said cartels operating there include La Familia Michoacana, the Knights Templar and the Zetas.
At least four mayors have been killed across Michoacan in the past four years.
Less than two weeks before Sunday's elections, gunmen killed La Piedad Mayor Ricardo Guzman Romero at a campaign event for Luisa Maria Calderon.
CNN's Krupskaia Alis and CNNMexico's Hanako Taniguchi contributed to this report from Mexico City. CNN's Catherine E. Shoichet wrote this story from Atlanta.