US presidential contenders Barack Obama and John McCain, trying to woo conservative Christians during a religious forum, differed on abortion, with McCain saying a baby's human rights begin "at conception," while Obama restated his support for legalized abortion.

The candidates shared their views on a range of moral, foreign and domestic issues during the event at Saddleback Church in California on Saturday.

The forum, during which Saddleback's influential pastor Rick Warren asked each candidate questions one-on-one for an hour and the two candidates briefly shook hands and hugged during the switch, was an opportunity for each to court an influential voting bloc in this November's presidential election.