Democrats in Virginia are investing heavily in data and field operations this election season in pursuit of victories in state races in November and the presidential campaign next year.Under the guidance of Gov. Terry McAuliffe (D), the party has hired dozens of field organizers and commissioned sophisticated surveys of the electorate for this fall’s state legislative races, in which Republicans are trying to hold onto a two-seat majority in the state Senate. The Democrats hope that the investment will pay off not just this year but also in 2016, when political observers expect Virginia to be one of the most competitive states in the presidential race.

The state party has 69 paid field staffers working on five competitive state Senate races, about 14 times as many as it did in 2011, the last time only state lawmakers were on the ballot. That’s 20 more staffers than U.S. Sen. Mark R. Warner (D-Va.) employed when he ran for reelection last year. Already, party operatives said, the infusion of cash has paid off: The newly hired staffers have called more voters, done more volunteer shifts and held more one-on-one meetings with potential volunteers than Warner’s staffers did in the statewide election.“We want to run elections like we do in the federal cycles, in the gubernatorial elections — we want to run those for all of the races we’re interested in this year,” said Brenner Tobe, who oversees data operations for the state party. “The increase in turnout and the number of people we can bring to the polls this year will be a huge lift for us in thinking toward next year.”

McAuliffe, a close ally of former secretary of state Hillary Rodham Clinton, has made no secret of his plans to help the Democratic front-runner win in Virginia. While he was all over the country and television as her campaign chairman in 2008, this cycle he is focused on building up an infrastructure for Clinton in Virginia. The state is expected to be a key battleground for both major parties; former Republican National Committee chairman Ed Gillespie has said the GOP won’t win the White House without winning Virginia.

Officials from both parties agree that data collection in Virginia is particularly challenging. More than a quarter of a million people leave the state each election cycle and a quarter of a million new people move in. There’s no party registration in the state, so campaigns start out essentially blind.

Democrats say they have records of party preference for about 65 percent of the electorate. To build out a model to predict the behavior of the rest, they have done deep surveys on 7,000 people, with over-sampling in competitive state Senate districts. They have a ranking for everyone in the state based on their likelihood to support Democrats and likelihood to vote. They’ve been able to compare that model with the current polling on each race to see whether their predictions for the electorate hold true.

“We have really identified everybody,” Tobe said.

The Analyst Institute, which helped President Obama’s reelection campaign aggressively test strategies, is consulting with state Democrats.

“That’s a big deal,” said Tom Bonier, a veteran of national Democratic data operations. “They’re sort of the mad scientists of the progressive movement.”

That level of sophistication didn’t come cheap. By the end of June, McAuliffe’s political action committee and the state party had spent several times what his two predecessors did on staff and consultants. New reports won’t be out until mid-October; the party will say only that several hundred thousand dollars has been spent.

Even with this investment, winning the state Senate will be a challenge for Democrats. Republicans have a strong and better-funded candidate running in Prince William County, where Sen. Charles J. Colgan (D) is retiring. In Virginia Beach, where Democrats are hoping to unseat Sen. Frank W. Wagner (R), their candidate has wounded himself by misrepresenting his military record.

It’s also the second-to-last year of Obama’s tenure. In 2007, when George W. Bush was nearing his seventh year in office, Democrats made historic gains in Virginia in part because of a national trend away from the GOP. Republicans see a similar White House fatigue this year, which is a boon for their party and a disadvantage for Democrats.

“It’s a reverse of 2007. We feel very good about the atmosphere that’s out there,” said Jeff Ryer, a spokesman for the state Senate Republicans. “We have every confidence that the governor . . . will be outspending us, but we also have a great deal of confidence in our own operation.”

A poll released Friday by Christopher Newport University backs up that confidence; likely voters support Republican Senate candidates by a 13-point margin.

And Democrats who have previously worked in Virginia said that while the state Senate effort sounds very solid, so were past campaigns in the state.

“I’d say that great programs in odd years are actually the precedent in Virginia,” said one campaign operative who spoke on the condition of anonymity, citing relationships with current staffers.

Republicans said their approach to organizing is different: They run their field operations through individual Senate campaigns, although state party Chairman John Whitbeck has also hired a dozen staffers to work the Senate races. In addition, the RNC has its own staff in each key area. And like the Democrats, the party has been training staff and volunteers in the kind of community organizing that was a hallmark of the Obama campaigns.

“We have the largest team on the ground that we’ve ever had,” said RNC spokeswoman Ali Pardo, and “every single thing we do is data driven.” She mentioned, for example, linking a person’s propensity to do yoga to their likelihood to vote.

Democrats say that relying on such consumer data is out of date and that the custom predictive models their party is using in Virginia are the future. “It’s likely just the front end of what you’re going to see in a lot of targeted state legislatures,” Bonier said. “This is the natural next step.”