By Andrew Cawthorne

CARACAS (Reuters) - Venezuela's opposition mocked President Hugo Chavez's chosen successor Nicolas Maduro on Friday as a "poor copy" of his boss who should be promoting national unity rather than insulting opponents during a delicate time for the South American nation.

In power since 1999, Chavez named vice president and foreign minister Maduro as his preferred replacement should he be incapacitated by the cancer he is battling in Cuba.

Since the December 11 operation, Maduro, 50, a former bus driver and union leader who shares Chavez's socialist politics, has been fronting day-to-day government in Venezuela while the president has been neither seen nor heard from in public.

Though lacking Chavez's booming charisma, Maduro has borrowed elements of his style - speaking regularly and lengthily on live TV, inaugurating public works, rallying supporters and attacking "bourgeois" opponents at every turn.

He even used one of Chavez's old catch phrases to gloat that Sunday's regional vote, where Chavez allies won 20 of 23 governorships, smashed the opposition into "cosmic dust."

The opposition Democratic Unity coalition reacted angrily.

"Vice President Nicolas Maduro has begun his temporary rule badly," it said in a withering statement, accusing him of ignoring Venezuela's pressing social, economic and political problems while falling back on antagonistic speeches.

"Mr. Maduro, the country expects better from you than a bad imitation of your boss. ... In his rhetoric, Maduro hides the leadership crisis in government given President Chavez's absence. He hides his weakness with shouts and threats."

"Don't waste the opportunity to create a wide national consensus," the statement said.

After an extraordinary year - in which Chavez proclaimed himself cured from the cancer that has dogged him since mid-2011, won a presidential election, then disappeared for new surgery - Venezuelans are heading into an uncertain 2013.

Government officials say Chavez, 58, is lucid and recovering in a hospital, but have acknowledged he is still suffering a respiratory infection after his operation and needs total rest.

Speculation is rife that his condition is life-threatening, and there is uncertainty over whether Chavez will be able to return to start his new term on January 10.

IN-FIGHTING?

The stakes are huge in Venezuela's political drama.

Beyond its borders, Venezuela helps sustain an alliance of left-wing Latin American governments from Cuba to Bolivia via oil subsidies and other economic aid.

Should Chavez be forced to vacate power, a new election would be held within 30 days, with the probable scenario a straight competition between Maduro and opposition leader Henrique Capriles, who lost to Chavez in the October vote. Continued...