BOGOTA - Colombians will choose mayors, governors and regional lawmakers in an election on Sunday which analysts say will serve as a referendum on the government of leftist President Gustavo Petro and could influence the 2026 presidential vote.

Sunday's vote is likely to emphasize the power of local and regional political families, as well as coalitions, rather than individual parties, according to analysts.

"There's a combination of factors. The opposition and traditional political sectors have tried to sell the elections as a referendum on the president and I believe that a lot of votes will be like that," said Green Alliance Senator Ariel Avila.

"There's going to be a big rap on the knuckles for (Petro's movement) Pacto Historico," he said.

Most candidates in Sunday's elections are backed by coalitions involving several parties or by signatures from citizens which allow them to run as independents.

"There's a very big dispute between traditional elites and new political forces. Most of the historic bosses have returned to the regions. Without a doubt, what's at stake here is the 2026 presidential campaign," Avila said.

Almost 39 million Colombians are eligible to vote on Sunday.

Campaigning has been marked by deteriorating security due to the presence of illegal armed groups - which remain active despite Petro's efforts to negotiate peace - and threats to candidates.

A recent report from the human rights ombudsman's office said more than 36% of municipalities face an extreme or high risk of violence during the elections, up from 23% in regional elections in 2019.

There is also a risk of electoral fraud, observers have warned.

"The main complaints have concerned irregularities on the part of serving public officials, and in advertising and the media," said Mauricio Vela, coordinator of advocacy group the Electoral Observation Mission.

"However, during election day the most reported crimes tend to be the buying and selling of votes," he said. REUTERS