There's a month left before the presidential primary in Pennsylvania, the next contest on the political calendar; 21/2 months until the end of the primary season in June; five months until the convention in August.

Party leaders not directly involved in the campaign would like to see the nominating fight between Barack Obama and Hillary Rodham Clinton resolved sooner rather than later, allowing the winner to focus on Republican John McCain.

But the drawn-out calendar and the overall tightness of the race won't allow it.

And the absence of primaries and caucuses, which were almost weekly events before, has a less-than-positive impact.

It excludes voters from a continuous and increasingly toxic loop populated solely by the candidates, their operatives, and the talking heads of cable television.

So until Pennsylvania holds its primary April 22, which looks at this point like a Clinton day, the nominating process spins its wheels and nerves get rubbed raw.

Consider the most recent exchange of conference calls, which happened Friday.

First, Obama's campaign manager, David Plouffe, accused Clinton of having "consistently engaged in political calculation to mislead voters" and said she'd be "a deeply flawed nominee" with "character issues that would cause us [Democrats] real problems in the fall."

Minutes later, Phil Singer, a Clinton spokesman, was saying of Obama: "He calls for high-minded debates while practicing low-down politics. . . . It's no wonder that top journalists are calling the Obama campaign desperate, saying that it's amateur hour in Chicago."

For now, Obama, the recipient of a welcome endorsement from former presidential candidate and New Mexico Gov. Bill Richardson, is holding a lead of roughly 120 delegates and 700,000 in the overall popular vote.

With a Florida revote dead and one in Michigan nearly so, it's increasingly difficult to see how he could lose those leads. Clinton was counting on victories in Florida and Michigan to help her overtake Obama in the popular vote and build her case that she is the stronger big-state, general-election candidate.

But Obama, who gave a memorable speech on race in America last week in Philadelphia, has had problems of his own lately, perhaps resulting from the underlying controversy over the remarks of his former pastor, the Rev. Jeremiah A. Wright Jr.

Several polls show Clinton gaining ground among Democrats nationally and running as well as or better than Obama does against McCain, undercutting the electability argument that has been central to the Obama campaign all year.

In addition, Clinton is holding double-digit leads in every Pennsylvania survey, although the race may tighten now that Obama (and not yet Clinton) is running television commercials throughout the state. Taken as a whole, said Clinton's chief strategist, Mark Penn, the trends "suggest a strong swing in momentum" in Clinton's direction.

By the time the Pennsylvania primary rolls around, it will have been more than two months (Feb. 19 in Wisconsin) since Obama won a primary in a state that's relatively large and that usually matters in November.

Clinton's advisers are hoping all of that will be noticed by the superdelegates, the nearly 800 party and elected officials who hold the balance of power in selecting the nominee. Said Penn: "Let's not try and rush the process."

The Obama camp points to the delegate totals and popular-vote numbers. Said chief strategist David Axelrod: "We don't want a protracted Democratic primary fight that diverts us from the ultimate mission, which is to defeat the Republicans."

Last week, Tennessee's Democratic governor, Phil Bredesen, himself an undecided superdelegate, proposed that the superdelegates meet in June, after the final primaries, and have a primary of their own.

If all of those delegates were forced to make a binding candidate choice then, the identity of the nominee would be known and the fight would be over, two months in advance of the convention.

The idea did not generate any groundswell of support.

The candidates themselves did not engage in much personal sniping last week. Obama gave his widely praised address on race. Both he and Clinton delivered thoughtful speeches on the war in Iraq. Clinton also put out a new plan to address the mortgage crisis.

As party leaders watch the race unfold, they are aware of one of the historical truths of modern politics: that an ugly and messy national convention in the summer usually leads to defeat in the fall.

The Democrats learned that in 1968, when there was disorder on the streets; in 1972, when there was chaos on the convention floor; and most recently in 1980, when the runner-up, Sen. Edward M. Kennedy, refused to shake the hand of the winner, President Jimmy Carter.

For the Republicans, defeat followed the Gerald Ford vs. Ronald Reagan convention fight in 1976. And prospects for a reelection victory by George H.W. Bush were lessened in 1992 by public reaction to the "culture war" speech delivered at the convention by defeated candidate Pat Buchanan.

So the desire to end the nomination fight before the Democrats assemble in Denver on Aug. 25 is widely shared, even by some prominent Clinton backers.

At a Clinton rally in Detroit last week, Sen. Debbie Stabenow of Michigan predicted: "When all these primaries are over - Lord, we can't wait until these primaries are over - we're going to come together."

That may or may not happen. If it does, it's not likely to happen as soon as many Democrats would like.