While Obama has been outspoken about his faith and its influence on his political decisions, Republican rival John McCain has been shy about sharing his own Christian faith.
An advisor to the McCain campaign had earlier explained that the Arizona senator does not want to use his personal faith for political gain, according to Christian Broadcasting Network.
Nonetheless, McCain has reached out to influential Christian leaders, including the Greek Orthodox head in America Archbishop Demetrios, and on Sunday, father-son evangelists Billy Graham and Franklin Graham.
Although McCain's campaign lacks the aggressive outreach of the Obama camp, polls show that he still leads by a wide margin among evangelical voters.
A CNN poll conducted by Opinion Research Corporation in June found nearly two-thirds of white evangelical voters surveyed (64 per cent) supported McCain, and 30 per cent backed Obama.
Notable, however, is McCain's significantly lower support from evangelicals as compared to Bush's 78 per cent in the 2004 election, according to exit polls.
"The evangelical community seems to be sitting on the fence to a particular degree," observed Jacques Berlinerblau, a professor at Georgetown University, according to CNN.
And that could open the door for Obama, he said.
"If Senator Obama can get between 30 and 33 per cent [of the evangelical vote] in those crucial swing states, he's absolutely golden," Berlinerblau said.
Obama is focusing his campaign this week on American values, including religious faith and patriotism, leading up to Friday's Fourth of July holiday.
