Modest opposition gains in state and local elections, coupled with sagging oil prices, could hamper President Hugo Chavez as he lays the groundwork for a new attempt to persuade Venezuelans to do away with term limits.

The opposition won five of 22 states up for grabs, including the two biggest — Miranda and Zulia — as well as mayoral races in the two largest cities.

The opposition's gains, however, did not dampen Chavez's ambitions.

"We've handed them a new defeat ... and a big one," Chavez said at a news conference Monday night, calling the results "a great revolutionary victory."

He said Sunday's vote showed that Venezuelans want him to press ahead with his socialist policies, and he hinted at a renewed effort to make constitutional changes that could expand his powers and let him run for re-election in 2012 and beyond.

Voters defeated Chavez's first attempt to scrap term limits in a referendum last year.

Chavez noted he is barred by law from relaunching the measures rejected in that vote. But he said his supporters could petition to abolish term limits if they choose and "then it would have to go once again to a referendum."

The opposition's gains are likely to force Chavez to come up with a new strategy to shore up support "before putting the proposal on the table again," said Luis Vicente Leon of the Venezuelan polling firm Datanalisis.

Leon said persuading voters to eliminate term limits could also be tougher for Chavez if low oil prices — the lifeblood of Venezuela's economy — force the government to significantly reduce public spending.

Plummeting oil prices have Venezuelan officials discussing possible austerity measures to hold spending in check.

Oil makes up 94 percent of Venezuelan exports and funds half the government's budget.

Last month, pro-Chavez lawmakers approved a $77.8 billion budget for 2009 based on average oil prices of $60 per barrel. Light, sweet crude for January delivery closed at $54.50 a barrel on the New York Mercantile Exchange on Monday, and heavy Venezuelan crude sells at lower prices.

Chavez says his government's tens of billions of dollars in reserves will help it cope and that it can adapt spending to the lower oil prices for an extended period if necessary.

The political opposition appeared emboldened after gaining ground in Sunday's vote.

Chavez's brother Adan was declared the winner in a close race to succeed their father as governor of Barinas. But opponent Julio Cesar Reyes challenged the result on Monday, urging his followers to "stay in the streets" and protest.

"We should defend the will of the people," said Reyes, a former Chavez ally whose renegade candidacy was boosted by accusations of corruption and government inefficiency in Barinas.

In the previous state elections in 2004, Chavez allies swept all but two of 23 governorships and a majority of local offices, while some opponents urged a boycott.

Chavez went into this vote with allies in 17 state houses after four governors split ways in clashes with the president. His allies won 17 gubernatorial races on Sunday.

But the defeat of a pro-Chavez candidate in Caracas' poverty-stricken Sucre district "destroyed the myth" that such areas are "bastions of support" for Chavez, said Jose Vicente Carrasquero, a political scientist at Simon Bolivar University.

The opposition also won governorships in Nueva Esparta, Carabobo and Tachira states.

Chavez's gubernatorial candidates together won 52.5 percent of the popular vote on Sunday, while their leading opponents came away with 41.1 percent, according to preliminary tallies with more than 95 percent of ballots counted.

After a decade in office, Chavez still is widely popular. But last year's defeat at the polls energized the opposition, which has also sought to capitalize on complaints about corruption and soaring inflation.

Chavez's dominance was especially apparent in poorer, rural states, while the opposition fared best in the affluent cities.