Sen. Barack Obama said he wants to expand the role of faith-based organizations in public life.

The presumptive Democratic nominee reached out to religious voters in a speech Tuesday. It was his latest effort to erode what has been considered a Republican base of religious voters.

Obama promised to overhaul President George W. Bush's Office of Faith-Based Initiatives, which he claimed has not fulfilled its mission.

Obama said that if elected, he'll start a new Council for Faith-Based and Neighborhood Partnerships to boost religious charities.

"The challenges we face today from saving our planet to ending poverty are simply too big for government to solve alone," Obama said.

His overtures to religious voters and willingness to wear faith on his sleeve stand out. Analysts said they think it's a lesson learned.

"The failure of Democrats to attract religiously observant voters has cost them dearly," said Bill Galston with the Brookings Institution.

Galston estimates that 25 percent of Americans are values voters for whom religious issues are the key factor -- many more call themselves believers.

Sen. John McCain is also reaching out. He has a director of evangelical research and has met with prominent religious leaders and, according to a recent poll, he has an edge.

A Washington Post-ABC News poll gave him 68 percent of the white evangelical vote, versus Obama's 22.

"Voters of faith are going to be an important element to this election," Republican National Committee Press Secretary Alex Conant said. "I'm confident they're going to vote for John McCain."

Yet McCain seldom speaks publicly on faith and faces suspicion among some religious conservatives. Galston said that is an opening for Democrats.

"A sense that the religious agenda is broadening," Galston said.

He said the agenda encompasses not only abortion and sexuality, among other things.

"But also environmental issues, international health issues," Galston said.

If it's true and Obama can tap in, that could make a difference in November.

In giving his speech Tuesday, Obama said he still "believes deeply in the separation of church and state."

Yet some critics of Bush's office of Faith-Based Initiatives said it threatened that separation and some said that about Obama's proposal. The group called Americans United for Separation of Church and State criticized the plan and said such programs undermine civil liberties.

Obama's speech on Tuesday was part of a series of speeches on values he has planned in the run-up to July Fourth.