While Barack Obama insists that his Democratic primary contest with Hillary Clinton is not over, the Illinois senator is looking ahead to the presidential general election, saying he’ll consider campaigning jointly with Republican John McCain this summer and debating him.

Clinton, whose campaign is $20 million in debt and in a tailspin, is becoming less of a concern for Obama as he sets his sights on McCain.

"We only have six contests left," Obama told reporters. "We are getting to the point where someone will be the nominee. We are not going to have a lot of time to pivot, and John McCain has been given a free pass. For the last two months, he has been able to go on various tours and make assertions that I think are questionable."

David Plouffe, Obama's campaign manager, affirmed Monday that for the first time since his campaign began, Obama has taken the lead among superdelegates.

"We've won more elected delegates, more states, and more votes than Senator Clinton. But until yesterday, we trailed among governors, members of Congress, and Democratic Party leaders -- the so-called 'superdelegates' who have a vote in the nominating process," Plouffe said in a statement.

"As it stands, we have 281 superdelegates who have committed to cast their convention votes for us," he said. "That includes 23 since last Tuesday's elections, and three who switched their support from Senator Clinton. We have just 150 delegates to go before Barack Obama clinches the nomination."

Obama said he'd be willing to campaign jointly with McCain, a suggestion from the GOP senator's camp, and debate him in town-hall style formats. But the back-and-forth barbs between the two men has already begun.

McCain, the presumptive Republican presidential nominee, has already started criticizing Obama, most recently for voting against John Roberts as Supreme Court chief justice, reaching out to the Christian right on one of its chief concerns: the proper role of judges in government.

"Senator Obama, in particular, likes to talk up his background as a lecturer on law, and also as someone who can work across the aisle to get things done," McCain said last week. But, he added, Obama "went right along with the partisan crowd, and was among the 22 senators to vote against this highly qualified nominee."

"Apparently, nobody quite fits the bill except for an elite group of activist judges, lawyers, and law professors who think they know wisdom when they see it, and they see it only in each other," McCain said.

And Obama, reading a speech to several thousand people at the Charleston Civic Center, said patriotism means more than saluting flags and holding parades. He criticized McCain for opposing a Democratic bill to expand education benefits for veterans.

"At a time when we're facing the largest homecoming since the Second World War," Obama said of veterans returning from Iraq and Afghanistan, "the true test of our patriotism is whether we will serve our returning heroes as well as they've served us."

The Obama campaign is also prepared to respond to attack ads by conservatives backing McCain, much like the so-called "Swift Boat" ads by Republicans that assaulted Sen. John Kerry in his presidential bid against President George Bush in 2004.

Although Clinton is heavily favored to win the West Virginia primary Tuesday by a large margin, she will not be able to win enough delegates by June 3 to cut into Obama’s significant lead. Clinton’s campaign -- which could end next month -- is struggling.

One Democratic strategist and longtime Washington insider told BlackAmericaWeb.com that Clinton’s campaign is on "life support." He said many superdelegates -- the group of Democrats who will decide the party's nomination for president -- have made their decision to support Obama but are withholding  public announcements until after the primaries on June 3 out of respect for Clinton. 

According to Politico.com, "Clinton is balancing a range of considerations: her bank account; her political future and the party’s; her need to win back Obama’s supporters, particularly African-Americans; and her need to keep faith with voters in her own (nearly) half of the party, many of whom have grown to dislike her rival.

"And so her options range from swift and gracious (although time is running out on that one) to the political version of Custer’s last stand: taking a losing hand to the Democratic convention in August."

Traci Blunt, a spokeswoman for the Clinton campaign, said Clinton is still in the hunt.

"We’re not slowing down," Blunt told BlackAmericaWeb.com Monday. "We’re moving forward until the end of the primary process."

Blunt said Clinton is still ahead in the polls in a head-to-head contest with McCain.

"She’ll continue to campaign, and she wants to prove to voters that she’s the most electable candidate," she said. 

With new supporters flocking to Obama's campaign every day, Obama also picked up a recent endorsement from Myrlie Evers-Williams, widow of civil rights leader Medgar Evers.

"Like my husband Medgar Evers and other great leaders of the civil rights movement, Barack Obama embodies a deep well of courage, integrity, compassion, strength and sound judgment," Evers-Williams said in a statement. "He offers the kind of leadership that we need in the White House as our nation grapples with chronic issues like rising gas and food prices, skyrocketing healthcare costs, a flagging housing market, job insecurity and a misguided Iraq war."

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Associated Press contributed to this story.