The promise of change propelled U.S. Democratic presidential candidate Barack Obama forward in the Iowa caucuses Thursday, while religion played a determining role in the victory of Republican candidate Mike Huckabee.

An Associated Press survey of caucus voters shows about half of participating Democrats said the ability to bring change was a pivotal factor in picking a candidate.

Central state of Illinois Senator Obama, who has stressed the need for change in Washington, drew support from 38 percent of Democratic participants in the first major test of the 2008 presidential election campaign.

The survey says faith was a key factor for Republican caucus voters. Nearly two thirds of supporters for former southern state of Arkansas governor and ordained Baptist preacher Huckabee said it was very important their candidate share their religious beliefs.

Turnout for the caucuses was much larger than in previous years, with more than 200,000 Democratic party participants and at least 116,000 Republican voters this year.

The higher turnout is partly because of the tightly contested races in both parties. This is the first time in more than 50 years that neither party has a current president or vice president in the running.

The caucus on the Democratic side allowed participants to switch their allegiance to another presidential hopeful if the candidate they supported did not have enough votes to be considered viable.

Some information for this report was provided by AFP and AP.