Gov. Bob McDonnell at the annual Wakefield Shad Planking in April 2009. (Tracy A. Woodward/THE WASHINGTON POST)

First there were the signs, lining the roads for miles to the dusty clearing in the Sussex County woods where the annual festival of bony fish, beer and backslapping known as the Shad Planking is held. Then there were the 100 campaign aides, and the banner of the plane streaking overhead — all urging attendees to back Terry McAuliffe in the 2009 gubernatorial race.

Four years later, McAuliffe (D) is running for governor again. But he and his entourage won’t be at Wednesday’s Shad Planking — the latest sign that one of the commonwealth’s quirkiest bipartisan traditions is morphing into something more typically partisan.

As he battles Attorney General Ken Cuccinelli II (R) — this year’s featured Shad Planking speaker — for the governorship, McAuliffe will be spending the day visiting a community college across the state. Sen. Timothy M. Kaine (D) skipped the event last year during his Senate race against George Allen (R), officially because he missed the deadline to accept a speaking invitation.

Since at least 1965, every Virginia governor has attended the Shad Planking the year he won election. With candidates, political operatives, activists and much of the state’s media all gathered on the same patch of ground, the event, held on the third Wednesday of April, was a fixture of the electoral calendar. Everyone went because everyone went.

So what’s changed? Mo Elleithee, a consultant who worked for Kaine in 2012 and McAuliffe in 2009, offered a blunt explanation.

“Shad Planking is a Virginia tradition that has totally and completely and utterly outlived its usefulness,” Elleithee said. “There are much better ways and much more productive ways to campaign in rural Virginia than going to an event where there are more Confederate flags than there are undecided voters.”

Shad Planking began in the 1930s as a small gathering to mark the migratory running of the shad — an oily, bony type of herring — in the James River. The Wakefield Ruritan Club has been organizing the event since 1949, using it as a fundraiser for community groups.

The gathering takes its name from its marquee dish: Shad that are nailed to oak planks and cooked slowly over an open fire. Last year’s gathering featured about 1,200 pounds of shad, 800 pounds of coleslaw and untold gallons of cold beer and iced tea, offered up by candidates and interest groups hoping to curry favor with the crowd.

Mirroring a broader shift in Virginia politics, the Shad Planking used to be dominated by conservative Democrats — particularly the “machine” of legendary Sen. Harry Byrd — before its more recent lurch toward Republicans. The crowd now clearly leans to the right, with a strong showing of tea party activists in the last couple of years.

The program traditionally includes speeches from big-name guests, who make jokes about the fish and gently rib each other. In 2009, Gov. Robert F. McDonnell(R) teased McAuliffe for “doing his part to stimulate the Virginia economy” with his profligate campaign spending.

Ellen Qualls, a senior adviser to McAuliffe, cautioned against reading too much into his absence this year.

“We had scheduled a visit to Blue Ridge Community College and we have been working actively to set up another college visit on the same day,” Qualls said. “There should be no significance read into it, and we hope the Ruritans have a great day.”

But Chris LaCivita, a Cuccinelli adviser who has been steering GOP candidates to Shad Planking for two decades, offered another theory.

“The reason why Democrats don’t go is because it’s in a rural area of Virginia, and they are very uncomfortable attending any event in a rural area because there’s a political disconnect,” he said.

The problem, some Democrats say, is that the event attracts folks who have long since decided how they’ll cast their votes. And the location — 50 miles southeast of Richmond and 160 from Washington — is not the most convenient. As Elleithee put it, it’s “in the middle of the day in the middle of the week in the backwoods of Virginia, where not a lot of people can get to it.”

Brian Moran, the former Virginia Democratic Party chairman, called Shad Planking “a cliche for old-time Virginia politics” that just “doesn’t hold the same importance as it used to.”

Moran did attend the event in 2009 when he was battling McAuliffe and state Sen. R. Creigh Deeds (Bath) for the Democratic gubernatorial nod. Deeds skipped the Shad Planking and won the primary, though he lost the general election to McDonnell.

Even Republicans are stepping away from one Shad Planking feature — the costly “sign wars.” Like McAuliffe did in 2009, campaigns have used the event to show off their organizational strength. But last year Allen decided to leave the signs at home and make a donation to the Ruritan Club instead. Cuccinelli will do something similar this year, though he’ll still be offering beer.

“I think it’s a definite pattern,” lamented Robert Bain, the chairman of the Wakefield Ruritan Club, adding that he did not know of any Democrats planning to set up hospitality booths this year.

Bain said the event has evolved over time: “Originally when my grandfather was going to this thing, it was all white males and everybody wore a coat and tie. Obviously that’s changed.”

But the loss of Democrats is an unwelcome development, especially because it means fewer tickets sold and less money raised for the local fire department and youth baseball, among other groups. And he’s not sure how to lure them back.

“I can’t think that they don’t like bony fish. . . . We’re scratching our heads — are we not displaying good manners or what?” he asked. “We’re just setting the table and inviting them to it.”