The campaign to succeed John P. Murtha is harkening to pre-primary days when party leaders selected a nominee and the decision stuck.

It was how Mr. Murtha himself, then a young Vietnam veteran and state assemblyman, secured his party's nomination to succeed John P. Saylor, a Republican who died in office in late 1973.

"It's obviously déjà vu," said James Alexander, a political science professor at the University of Pittsburgh at Johnstown who was a new faculty member when Mr. Murtha first won election to Congress.

This time, there are a few twists, notably the presence of a female hopeful and the fact that the special election to replace Mr. Murtha will take place at the same time as the nominating primary for a full term representing the 12th Congressional District.

"Last time they simply stuck with the original special election nominees in the general election. This time they don't have enough of a time gap to consider nominees for November," Dr. Alexander said.

Ostensibly, seven candidates are seeking spots on two ballots for the special election to fill the unexpired term of the veteran congressman, who died Feb. 8.

Each party has a series of procedures in place to choose a nominee for the vote, which will take place alongside the May 18 primary, meaning that voters will be asked to elect a member of Congress while at the same time choosing a party nominee for that same seat in the November election.

It raises the specter of a person being elected to office but not nominated for the subsequent November general election. It also offers an interesting test of how closely the party leaders have gauged the mood of their rank-and-file voters and whether their judgment in the special election will be overturned by the voters in the simultaneous primary.

"It's an interesting situation," said Dante Bertani, longtime chairman of the Westmoreland County Democrats.

"It means we'll have a candidate running against a Democrat and a Republican at the same time. That's wild, isn't it?" said Rob Gleason, the state Republican chairman.

Already, Democratic and Republican leaders are signaling preferences that could presage a quick decision.

On the Republican side, several important county chairmen as well as the National Republican Congressional Committee have signaled early support for Tim Burns, a Washington County businessman.

His lone significant challenger is William Russell, a retired Army officer who mounted a strong challenge against Mr. Murtha in the 2008 general election. Party insiders, though, suggest that Mr. Russell's appeal was as a vote against Mr. Murtha at a time the Democratic incumbent was under fire for a number of gaffes.

With Mr. Murtha now gone, Mr. Russell's brigade might have withered, and some conservative groups, including the influential Red State blog, have gone on record backing Mr. Burns.

"I know Burns has been working the party infrastructure, going around and meeting party chairmen, committee people, going to Tea Party people," Mr. Gleason said.

Kent Gates, a political consultant and Cambria County native, is managing the Burns campaign and confirmed the outreach to party elders.

"Tim's taking this process very seriously," Mr. Gates said. "He has worked hard the last eight months to build up support within the party."

What Republican leaders are clearly hoping for is to wrest the predominantly Democratic 12th the way the GOP overturned the registration edge in Massachusetts to take control of the seat held for 48 years by the late Edward M. Kennedy. There, Scott Brown, a political unknown, put a Republican in a Senate seat for the first time since Edward Brooke was unseated by Paul Tsongas.

"I have to win this," said Mr. Gleason, the GOP chairman and Johnstown resident. "The whole country's looking to me. If Scott Brown can do it, why not Rob Gleason?"

On the Democratic side, the remnants of the powerful political machine Mr. Murtha built during 36 years in Congress have coalesced around his former district director, Mark Critz. Additionally, Mr. Critz now enjoys the endorsement of Mr. Murtha's widow, Joyce, who turned down an invitation to run for the seat herself.

That advantage could be mitigated by one major factor -- Barbara Hafer.

Ms. Hafer, the former auditor general, state treasurer and 1990 Republican gubernatorial nominee has announced plans to seek the nomination, both from the state committee and from the voters in the primary. Her chances at the nomination for the special election could hinge on women rallying around her and whether Gov. Ed Rendell will weigh in on his own preference.

Two other candidates -- Ryan Bucchianeri, a Washington County businessman; and Ed Cernic, the Cambria County controller -- also have announced plans to seek the Democratic nomination.

Even if the Democratic field looks crowded, it was thinned considerably by the withdrawal last week of three other hopefuls. Mark Singel, the former lieutenant governor, announced he would not run, as did Westmoreland County Commissioner Tom Ceraso and Albert Penksa, the former Cambria County controller.

Westmoreland represents the single, largest vote block in the district, with Cambria following. Those withdrawals likely narrowed the contest to a footrace between Mr. Critz and Ms. Hafer.

The Republican nominee will be selected by a meeting of conferees chosen by county chairs from within the district. Their vote will be binding.

On the Democratic side, a straw vote is scheduled for Saturday, but the ultimate nomination is made by the 50-member executive committee of the state party -- meaning the nominee will be chosen by party officials from outside the district.

It also raises the question of Mr. Rendell's preference.

He owes Ms. Hafer a large favor. She broke with the Republican Party in 2002 to endorse Mr. Rendell over Republican nominee Mike Fisher. Later, she quit the GOP altogether and became a Democrat.

"I think it's obviously a tossup between Mark Critz and myself," Ms. Hafer said. "I'm in regardless, even if I don't get the special nomination. My strategy is if I don't finish the term, I'm still in for the two-year term."

Mr. Critz, who describes himself as a conservative Democrat -- pro-gun and anti-abortion -- is hoping that long-standing connections throughout the district, both as a Murtha campaigner and, later, as a Murtha aide, will pay off when Democratic conferees convene for their straw vote.

"The tack that I've been taking is that I'm going to go to that convention and win it big so that the state committee, although they are not obligated to follow the wishes of the convention, have no choice but to follow that," he said.

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