Poll setback for Mexican leader

Some 77 million Mexicans were registered to vote

The centre-right National Action Party (PAN) of Mexican President Felipe Calderon has admitted defeat in mid-term congressional elections.

It acknowledged that the opposition Institutional Revolutionary Party (PRI) will dominate the Lower House.

The PRI dominated Mexican politics for seven decades until 1997.

The campaign was overshadowed by a collapsing economy, and the government's drive against drug gangs.

Mr Calderon won a bitterly fought presidential election three years ago promising reforms to restore economic growth.

We're in the worst crisis Voter Salvador Zavala Mexicans hit hard by US woes Taking on Mexico's kidnap gangs

Mexico has been badly hit this year by the global recession and a drop in the amount of money sent home by migrant workers.

The outbreak of swine flu in April has also scared off tourists, which the government has warned may cost the economy more than $2bn (£1.2bn).

"We're in the worst crisis," Salvador Zavala, 66, told Reuters news agency as he voted north of the capital, Mexico City.

If the PRI is able to form a majority, it could block the president's efforts to give more powers to the 45,000 soldiers deployed to root out the country's powerful drug cartels, AP reports.

The PRI was in power for nearly seven decades until losing its majority 12 years ago.

Mexicans were electing 500 members of the Chamber of Deputies, the lower house of Congress, as well as six state governors and hundreds of mayors.