Washington - The faltering US economy was by far the top concern of voters heading to the polls in Tuesday's general election in the United States, according to initial exit polls.

A full 62 per cent of voters ranked the economy as the key issue of this election, compared to 10 per cent invoking the war in Iraq and 9 per cent rating terrorism or health care highest, exit polls by US broadcaster CNN showed.

The economic focus of the last few months was widely considered to have helped Democratic candidate Barack Obama take a strong lead in opinion polls over Republican rival John McCain.

Voters typically show more confidence in Democrats on managing the economy, especially after eight years of a Republican administration, but rate Republicans higher in handling national security and foreign policy.

More than 90 per cent of voters rated the economic conditions as "not so good" or "poor," according to polling by NBC. The US government reported third quarter gross domestic product contracted 0.3 per cent and many economists expect the world's largest economy is headed toward recession.

But in another indication that may work in McCain's favour, exit polls reported by ABC News said 13 per cent of voters were African American, only slightly higher than 2004. Obama, who would be the first ever African American president, was relying on a strong turnout from minority groups. (dpa)