What if Virginia held an election and nobody came?

The outlook for Tuesday isn’t quite that stark. But owing to the quirks of the state’s calendar — which produces a ballot every four years featuring no federal or statewide races to drive turnout — there is a good chance that fewer than one-third of Virginia’s voters will show up at the polls.

That dim forecast comes despite the fact that control of the state Senate hangs in the balance and with it the possibility that Republicans could soon control all the levers of power in Richmond. Northern Virginia, in particular, will be the scene of a handful of close matchups, but those will be the exception rather than the norm because new redistricting maps have created a host of General Assembly seats where one party or the other didn’t field a candidate.

“Only about one-third of legislative races are even contested, so we’re looking at extremely low turnout,” said Michael McDonald, a George Mason University professor who studies voting behavior. “Most of the state is not looking at a competitive election.”

In 2007, the last similar election, just 30 percent of registered voters cast a ballot. In 2003, the number was 31 percent. By comparison, turnout was 44 percent in 2010, when several congressional races were in play; 40 percent in 2009, with a governor’s race atop the ballot; and 75 percent in the 2008 presidential election.

In a cycle such as this one, large majorities of moderate and independent voters are expected to stay home, leaving the most conservative Republicans and liberal Democrats to battle it out. So both parties are working overtime to turn out their base voters.

That helps explain why Northern Virginia Democrats, for example, are attacking Republican candidates on social issues such as abortion and gun rights and why President Obama’s reelection campaign e-mailed supporters in the state last week urging them to work a weekend shift making calls and knocking on doors.

“There are no ‘off years’ in Virginia. . . . These are critical elections to the future of our commonwealth,” said Brian Coy, spokesman for the Virginia Democratic Party, adding that the state’s voters know the Senate is up for grabs and that they “understand that Virginia Democrats are the only voice of moderation in state government.”

Citing public and private survey data, Republicans argue that momentum is on their side.

A mid-October poll taken for Christopher Newport University and the Richmond Times-Dispatch showed that 70 percent of registered voters said they were paying “little” or no attention to the November 2011 elections.

Among the 28 percent of voters who said they were paying “some” or “a lot” of attention to the elections, 49 percent said they planned to vote for their local Republican state Senate candidate, while 34 percent planned to vote for the Democrat.

“In the districts where you have legitimately competitive races, the Republican electorate is more animated and more excited and clearly have an advantage from a turnout perspective, and the Democrats can’t deny that,” said Chris LaCivita, a consultant who is working for several Republican candidates on Tuesday’s ballot.

On the national level, voters are worried about the economy and unhappy with leaders from both parties. But the dynamic is a bit different in Virginia.

In the Christopher Newport poll, 46 percent of respondents said they thought things in Virginia were heading in the right direction, but only 15 percent said the same about the direction of the country. Gov. Robert F. McDonnell (R) remains broadly popular, according to several recent polls.

“Virginians generally think [McDonnell] is doing a good job and the state is moving in the right direction. . . . I think that will have some impact and encourage some independents to come out and vote for Republicans,” said Dave Rexrode, the executive director of the Virginia Republican Party.

Turnout can vary widely in different parts of Virginia. In 2007, for example, turnout in the 20th District Senate race, in the southwest portion of the state, was 45 percent, and in the Arlington County-based 31st District, it was 25 percent. Neither race was particularly competitive.

Beyond reducing the number of competitive seats, redistricting could diminish turnout in another way, said State Board of Elections spokeswoman Susan Pollard.

“One thing we do anticipate is that there may be some confusion with where people go to vote, so we are strongly encouraging people to check their polling places before they go out on Election Day,” Pollard said.

Virginians can find their voting locations for Tuesday at www.sbe.virginia.gov. The polls will be open from 6 a.m. to 7 p.m.