"The one thing you all share, is a moral conviction, you know, that this debate over health care goes to the heart of who we are as a people," said Obama on the call also including his domestic policy director Melody Barnes.
"I believe that nobody in America should be denied basic health care because he or she lacks health insurance," Obama said, after calling into a webcast including clergy and believers of Evangelical, Protestant, Catholic and Jewish orders.
"No one in America should be pushed to the edge of financial ruin because an insurance company denies them coverage," Obama said.
Obama hit out at what he branded "fabrications" whipped up by opponents of his policy, including claims that it would expand abortions, give health care to illegal immigrants and ration end-of-life care.
"These are all fabrications that have been put out there in order to discourage people from meeting what I consider to be a core ethical and moral obligation.
"That is that we look out for one another, that I am my brother's keeper and I am my sister's keeper," Obama said, using a phrase drawn from the Bible.
Republican National Committee chairman Michael Steele dismissed Obama's call as a gimmick, saying it was evidence the White House was running scared.
"President Obama is frantically struggling to shore up his base," Steele said.
"The religious left talks about their desire for ‘social justice.’ No bill that funds abortion or strips health care services away from seniors and low-income Americans can or should be considered just," he said.
The White House earlier denied it had given up wooing Republican support for Obama's plan, following reports Democrats may go it alone.
"The president has said countless times he will work with anybody in any party that wants to work constructively on health care reform," said White House spokesman Robert Gibbs.
Expectations that the Democrats would fall back on their majorities in the House of Representatives and the Senate to pass the bill were fanned by several media reports late on Tuesday and early Wednesday.
The New York Times quoted White House chief of staff Rahm Emanuel as saying the Republican leadership had made a strategic decision to defeat health care reform, Obama's signature domestic initiative.
But Gibbs said Obama was committed to engaging with Republicans in pursuit of a bipartisan measure.
"There are still several more weeks to go in potential negotiations between Republicans and Democrats. I don't know why we would short-circuit any of that."
Obama would like to win some Republican support for his bid to cut health care costs, expand access and rein in insurance giants, in line with his vow to drain the partisan bile from Washington.
Some polls suggest that most Americans would like a bipartisan solution.
Republican votes may also give vulnerable lawmakers from conservative Democratic districts some cover to vote for the measure, or leeway to oppose it without endangering its chances of passing Congress.
Gibbs said he believed there were some Republicans still working in a "constructive" way to promote health care reform during the August congressional recess.
"We will get in a rocket and fly around the moon if that is what it takes to get everybody together and get an agreement," Gibbs said.
After spending last week repulsing Republican attacks on the health care reform drive, Obama is now facing a liberal backlash, following reports, denied by the White House, that he is prepared to drop a plan for a government-run entity or "public option" to compete with private insurance plans.
In a sign of an intensifying sales job, Obama has lined up a live online and telephone meeting with Organizing for America, the network of millions of grass roots supporters which emerged from his 2008 campaign infrastructure.
The White House said that the president would appear live to take listeners calls on the radio show of conservative commentator Michael Smerconish on Thursday.
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