Venezuelan President Hugo Chavez marks the mid-point of his six-year term Tuesday, when, according to the constitution, he could be recalled in an election.
News reports say the president's opponents plan a large march through Caracas this week. They are expected to give electoral officials nearly three million signatures calling for a referendum on the president's rule.
A counter-demonstration also is expected in Caracas as tension rises in the world's fifth-largest oil exporter.
President Chavez's opponents say he has wrecked the economy and is trying to model the country after communist-run Cuba.
In December, the opposition began a two-month general strike in a failed bid to force him to resign and call early elections. Mr. Chavez blames Venezuela's economic downturn on the failed strike.
In April of last year, the Venezuelan leader was briefly ousted in a short-lived military coup. Troops loyal to Mr. Chavez quickly restored him to power.
The Organization of American States has been active in trying to help resolve Venezuela's political crisis.