Venezuelan President Hugo Chavez returned to Cuba for more cancer surgery, which may mean he'll miss his inauguration for a new presidential term next month.

The president went on national television over the weekend to announce his cancer had returned. For the first time in his two-year battle with the disease, Chavez said if he suffers complications, Venezuelans should choose Vice President-elect Nicolas Maduro as president, his long-time ally with close ties to Cuba.

Calling for "unity" in the days ahead, Chavez told the country Maduro could lead Venezuela's socialist revolution should his health prevent him from continuing in office.

As he flew back to Cuba, Venezuela's political uncertainty deepened. If he is unable to take the oath of office on January 10, the constitution calls for new elections within 30 days of his resignation.

Political observers believe Chavez' party could split if the leader of parliament also decides to run for president, giving the opposition party another chance to win.

Chavez has never revealed what type of cancer he's battling.