With the odds increasing that they will not have a clear presidential nominee before June, Democratic Party leaders are preparing for the possibility that they might have to plan the remainder of their national convention without a candidate.

Yet, convention planners, party leaders and Democrats in the House and Senate say they still have plenty of time to pull it together before the four-day event begins in Denver in late August. Those officials argued that they have done enough legwork to be ready to kick off the convention even if neither Sen. Hillary Rodham Clinton (N.Y.) nor Sen. Barack Obama (Ill.) secures the nomination beforehand.

“The nuts and bolts, the logistics of the convention are the logistics, regardless of the nominee,” said Leah Daughtry, chief executive officer for the Democratic National Convention. “On Aug. 25, we have to be ready. We don’t get another day. We’re planning to be ready in that hall when that gavel drops.”

Daughtry said organizers got off to “an early start” with the selection of the convention dates and location. Also, she said party officials continue to be “on pace or ahead of pace in terms of planning and logistics.”

Much of the preparation has been under way for months, with national Democrats working to make available lodging, transportation and convention space for the thousands of visitors to Denver. Most of that work can be done without the presidential nominee in place, but the candidate typically teams with national party players well in advance to put his or her stamp on the overall message, framework and program for the four-day event.

The presumptive Republican nominee, Sen. John McCain (Ariz.), already has dispatched his staff to coordinate with the Republican National Committee to help organize his party’s convention. The GOP holds its nominating event in Minneapolis beginning Sept. 1.

McCain’s head start in planning what’s typically a ceremonial exercise is just the latest example of how a protracted Democratic primary could create challenges for the party in the coming months. As Obama and Clinton fight for delegates, many Democrats have voiced concern that the lengthy campaign could hurt party unity and lessen their chances to take back the White House in November.

Also, Democrats still are wrestling with whether and how to seat delegates from Michigan and Florida, where officials defied the Democratic National Committee and held their primaries too early. The DNC so far has refused to allow delegates from the two states to participate based on those earlier primaries, both of which favored Clinton but in which neither candidate campaigned.

Even with all those elements in play, party insiders say they don’t believe Obama and Clinton will continue to do battle until they convene in Denver. Still, they say, they are planning for every contingency and insist it won’t take long for the Democratic nominee to line up preferred convention speakers and coordinate his or her theme, message and ideas with the event.

“There’s still plenty of time,” insisted Sen. Ken Salazar (D-Colo.). “The convention planning is moving with full force; we are way ahead of Boston and L.A. The logistics — all that is happening.”

“Even if this goes to a brokered convention, there’s so much excitement that will make it successful,” Salazar added. “Those of us on the executive committee will deliver a quality convention.”

Several senior Democrats recalled that their White House pick and later President Bill Clinton didn’t secure his party’s nod until June 1992, just a few weeks before that year’s Democratic convention was held in New York. That nominating event proceeded as planned, with no major hiccups, they argued.

“It’s only March and the convention isn’t until August,” said Rep. Diana DeGette (Colo.), whose district includes the host city of Denver.

Sen. Debbie Stabenow (Mich.), whose state could play into the length of the primaries, said delays have happened before and that “things will work their way out.” Stabenow argued that the competitive nature of the Democratic contest is actually paying dividends for the party since “people are so engaged.”

“They aren’t upset about there being two people,” she said. “I think it will all come together.”

Rep. Stephen Lynch (D-Mass.), a convention veteran who helped play the role of host in Boston four years ago, said that despite the uncertainty of the race, he also doesn’t believe the 2008 convention will be affected. Lynch predicted that Democratic officials would do a “carve out” to ensure the nominee — whomever emerges — would have flexibility in planning once he or she is named.

He noted that many of the DNC aides charged with filling the podium and setting a speaking order have experience to pull it together, having played the same role since the nomination of former President Jimmy Carter. Daughtry, in particular, has been involved in the Democratic events for more than a decade.

“All outward appearances are it’s going well at this point,” Lynch said.

As it stands, few in the national party leadership want to consider as reality the prospect that the Denver convention actually will require a formal head count between Obama and Clinton. But if ballot counting does ensue, Democrats would defer to DNC Chairman Howard Dean, House Speaker Nancy Pelosi (Calif.) and Senate Majority Leader Harry Reid (Nev.) to wade through final preparations typically reserved for the nominee.

“It may come to that,” acknowledged Brendan Daly, spokesman for Pelosi. “But the Speaker is hopeful we’ll have a nominee by the time we get to the convention.”

Daughtry said convention organizers “think we’ll be walking into Denver unified and knowing who our nominee is. We aren’t at all worried about that.” She added that even under the worst-case scenario, the Democratic leadership could pull it off since many decisions require little debate, such as a speaker lineup, that undoubtedly will include Pelosi, Dean, Reid and Colorado Gov. Bill Ritter.

“It’s really not this big hullabaloo,” she said.

Some other determinations, such as themes, could progress on schedule given the similarities between the candidates on issues such as health care, the economy and Iraq, predicted Rep. John Salazar (D-Colo.).

“I think we’re all on the same page, or similar pages,” Salazar said. “I don’t think there’s a difficulty in really organizing the convention.”

Even so, grousing over the convention planning is likely to come, especially from Members of Congress gunning for plum hotel rooms and credentials to accommodate themselves, their donors and their friends. Denver likely will be no different, especially given the heightened interest by the media and the public over who will emerge as the Democratic candidate.

“In terms of the mechanics, the logistics, there are always some people who aren’t particularly satisfied,” said Rep. Bill Delahunt (D-Mass.), who assisted with the host role in 2004.

But Ken Salazar was quick to point out that Denver is no rookie to event planning, arguing it has handled, among other things, an international G-8 summit and a papal visit.

“We know how to do these things,” he said. “I have no doubt.”