WASHINGTON — The Democratic presidential nominating process is now at a decisive juncture, said the Rhode Islander who helped create the process.

Tad Devine, the Democratic delegate maven, told a seminar this week at American University in Washington, D.C., that superdelegates will probably decide who will be the Democrats’ candidate for president.

Of the 796 superdelegates — governors, members of Congress and other party leaders — nearly 400 are still undecided, including Sen. Jack Reed. Practically the only consensus is that a nominating battle in Denver between Senators Hillary Rodham Clinton and Barack Obama would hurt Democratic chances of victory in November.

Reed, a strong partisan who has a history of moving cautiously toward endorsements, remains inclined to stay on the fence while the remaining primaries proceed.

“We should try to get this resolved sooner than August,” Reed said in an interview this week. But he offered no certainties about how he and his fellow superdelegates should proceed — particularly those who have not chosen between Clinton and Obama.

“I don’t have a good idea about how we ought to go” if the race remains undecided after all the remaining state elections have been held. But like other House and Senate members, Reed is cool to mechanisms that, in the words of Sen. Sheldon Whitehouse, “would try to force anybody’s hand” by fixing deadlines for endorsements, for example, or penalizing delegates who remain neutral.

Like many other Democrats, Reed and Whitehouse also argue that the furious Clinton-Obama contest helps to kindle voter interest, raise money, frame issues for the general election and otherwise help the cause of the eventual nominee. “This is very good advertising for us,” said Devine, a political consultant who was involved in some of the negotiations that created the current Democratic system.

“This is the most exciting nominating convention of my lifetime,” said Rep. James R. Langevin, a Clinton supporter who agrees that the contest is good for the party — up to the point, that is, that it does more to divide than unify Democrats.

Defining that point is not easy, but the arithmetic of the nominating impasses is straightforward. With about 3,150 Democratic delegates chosen so far for this summer’s party convention in Denver, Obama now has an edge of roughly 150 delegates, by most counts. But barring some shocking event, there are not enough delegates left to be elected for Obama to win a nominating majority of the 4,049 delegates. The undecided superdelegates hold the remaining numbers to create a majority.

The same math suggests that Clinton would be very hard-pressed to overtake Obama, let along seize a nominating majority.

THE SUPERDELEGATES were created to guarantee a role for party elders after contentious conventions that relatively few of them attended. The idea was that those members of Congress and other leaders granted super status would exercise their judgment to protect the interests of the party at large as well as offering “expertise in politics and government.”

Back from a two-week recess and with the next key contest less than two weeks away, congressional Democrats are buzzing about how that contest will play out, Langevin said. But he said there is no agreement about how or when the undecided superdelegates ought to move, he said.

As the front-runner, Obama has a clear interest in minimizing their power to shift the scales against him, while underdog Clinton’s best hope is to keep that bloc fluid as she battles for advantage in the remaining 10 primaries and caucuses to be held by early June — which start a week from Tuesday with perhaps the most important vote, Pennsylvania’s primary. Langevin, Whitehouse and the undecided Reed have all expressed the hope to see the process through to that point.

Like their candidate, Whitehouse and Langevin both reject the suggestion that Clinton’s path has become so steep that she should end her campaign for the good of the party.

Reed, Langevin and Whitehouse did not embrace the proposal of Tennessee’s Democratic Gov. Phil Bredesen to set up a June meeting of superdelegates to conclude a campaign that, in his view, is damaging Democratic chances.

Devine said that, provided such a meeting is “transparent” and open to the news media, it could help precipitate a useful movement of superdelegates en masse to one candidate or the other.

Anthony Corrado — a professor of political science at Colby College who is a longtime associate of Devine and another Rhode Islander — argued that a pre-convention meeting of superdelegates could play into “concerns that party leaders are somehow going to take away the voice of the voter that would be symbolized by this convocation.”

Rep. Patrick J. Kennedy, who could not be reached yesterday, is a prominent supporter of Obama. In January the Rhode Island Democrat shared an endorsement event with his father, Sen. Edward M. Kennedy, and his cousin, Caroline Kennedy. He said at the time that these endorsements could help Obama make inroads into some of Clinton’s areas of strength — Hispanic and blue-collar voters, for example. That has indeed happened in some states but not enough to create a decisive swing away from Clinton.

jmulligan@belo-dc.com