By Michael H. Cottman

Barack Obama insists that his Democratic primary contest with Hillary Clinton is not over, but in the meantime he's looking ahead to the presidential general election and considering an invitation to debate Republican John McCain this summer.

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.

For Obama, Clinton was a worthy opponent but now -- for all practical purposes -- she is a rival of the past as Obama moves on to the next round. 

Although Clinton is heavily favored to win the West Virginia primary, 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 said the Clinton 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 their public announcements until after the primaries are completed on June 3 out of respect for Clinton. 

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

"We're not slowing down," Blunt said. "We're moving forward until the end of the primary process."

The Clinton campaign has modified its language. A few weeks ago, aides insisted that Clinton was in the race until the Democratic National Convention in August. 

There are those who suggest that Clinton cannot exit the race gracefully, that she has to fight to the end even if the party is damaged and split along racial lines in the process.

Time is running out for Clinton.

Obama has picked up 26 superdelegates in the past week. He's now on track to reach 2,025 - the number of delegates needed to clinch the nomination - in the next three weeks. 

There are six remaining primaries - West Virginia, Kentucky, Oregon, Puerto Rico, Montana and South Dakota - and 217 delegates at stake. Even if Clinton wins most of those delegates, Obama could reach 2,025 and secure the nomination.

There are signs that Clinton may be mellowing. She is not as combative on the campaign trail and she's not attacking Obama with as much furor. 

Obama says it's important for the primary process to continue and does not want to be perceived as nudging Clinton out of the race because he'll need her supporters in November if he becomes the Democratic nominee.

"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."

For a man who maintains that he's still in a primary fight with Clinton, he's sounding more and more like a candidate who has extended the battlefield into the general election.