The presidential primary campaign is at a “tipping point.” This reference is not to the virtual inevitability of the few remaining delegates toppling into the Obama column, thus making him the Democratic nominee.  Rather, I believe that both Democratic candidates have reached an historic opportunity to tip this contest into an irreversible general election victory.

The hard truth is that in this closest of all presidential primary election contests both Barack Obama and Hillary Clinton must rely upon the other if either is to take the Oval Office.  And as the frontrunner, Obama needs Clinton more than she needs him.  Out of 34 million votes cast, he has only 300,000 more than she does.

Both candidates have their own extraordinary electoral strengths.  Obama’s has been receiving an astonishing 90 percent of the African American vote and more than 60 percent of young voters.  Hillary has totaled more than 60 percent of older voters and is also the runaway favorite of Catholics voting in the Democratic primaries.  The obvious problem for both candidates is that their supporters are expressing, for now at least, their reluctance to vote for the other candidate if he or she is the eventual nominee.  Neither Hillary nor Barack can become president without these voters, a full 70 percent of whom have told the exit pollster they will not vote for the Democrat in November if their chosen candidate is not the nominee.  If only 10 percent of that threat is realized, it will doom the Democrats in November.

Since the beginning, this exciting, compelling campaign has engaged people in important, meaningful democratic participation.  For the young, politics has become cool and for millions of others, it is once again important to our individual lives.  But, what has now occurred in this passionate primary campaign is that the supporters of each candidate have become so partisan, determined and stubborn that they might assure the defeat of their party in November.

So this campaign has reached the tipping point, the time when both the candidates and their supporters must take the road which seems counterintuitive to normal campaign activity but will be critical to winning.

Does this mean that Mrs. Clinton should quit?  Absolutely not.  To use a golfer’s analogy:  this woman matched the men drive-for-drive and putt-for-putt.  She played from the men’s tees and her only insistence is that the match continue through all 18 holes.

What the tipping point requires is a new campaign civility, a show of genuine admiration between the candidates but, equally important, from their supporters as well.  Each camp must reach out to the other in real friendship.  Barack Obama’s life story, including his incredible surge in America’s politics, deserves recognition.  Hillary Clinton’s intelligence and pure grit is the stuff of the American experience.  We should rejoice in these choices and they should meet the occasion with public expressions of respect for each other.

During the final month of this primary campaign, the candidates should have joint appearances, as many as possible.  Here in Montana the suggestion has been offered for a Lincoln-Douglas Debate.  Such an event would show the candidates off at their best.  With no press to ask and monitor the questions, with the candidates free to pose their own questions of each other and without time limit interruptions, we would observe them as they are.  Similar events in the five remaining states and Puerto Rico would permit a free-flowing discussion of their differences on the issues without the jarring disruption of the planted questions about flag pins or the statements of either candidate’s spouse.

Because this year’s contest has been remarkably free of the nastiness that has characterized so many other campaigns, Democrats still have a chance to encourage their disappointed voters to join together.  But it will take a significant effort to unite young and old, black and white, who for a year-and-a-half have grown more and more determined that their candidate, and only their candidate, deserves to be elected.  Either Hillary Clinton or Barack Obama have the stuff to be a fine and perhaps a great president.  Now is the time for them to demonstrate that capacity.

Pat Williams served nine terms as a U.S. Representative from Montana.  After his retirement, he returned to Montana and is teaching at The University of Montana where he also serves as a Senior Fellow at the Center for the Rocky Mountain West.