"The campaign is reaching out to a number of faith communities. It's not just targeting one or two. They have a staff of six or seven people doing various kinds of outreach, and if you were to add it all up, it would cover most American faiths," adviser Shaun Casey said.
"This is...an expansive and inclusive religious outreach strategy," Casey told Reuters in a telephone interview from Nashville, Tennessee, where he is attending a conference of Christian scholars at Lipscomb University.
In the United States, many people regularly attend religious services and most Americans surveyed say they believe in God. A majority of the population is Christian.
To connect with religious voters, politicians often visit church congregations, pepper their speeches with Biblical references and discuss ways their faith has shaped their views and actions.
In recent election cycles, the Republican Party has galvanised white conservative evangelicals by playing up candidates' positions on social issues like abortion.
Arizona Senator John McCain, the presumptive Republican nominee for the November presidential election, is regarded with suspicion by this base for a number of reasons, including his past criticism of conservative evangelical leaders.
Obama's support for abortion rights and his voting record in the US Senate means the presumptive Democratic presidential nominee will likely make few in-roads with conservative evangelicals who have begun to attack him.
But analysts have said Obama, who would be the first black president, can woo more centrist evangelicals and Catholics, whom polls suggest have been moving from the Republican camp into the growing independent ranks.
Young religious voters are a group that the Obama campaign will target with a grassroots project.
"That is a tool the campaign will use to reach young, religiously motivated voters...He (Obama) has energized that under-30 generation and a lot of those folks are in fact religious themselves," Casey said.
