This is part of a series of articles on the Aug. 23 General Assembly primary elections in Northern Virginia. The series will appear through August.

Republicans in Northern Virginia hope to defeat a pair of incumbents as they attempt to wrest control of the state Senate from Democrats in November.

Four Republicans are competing in Tuesday’s primary to take on Democratic Sens. George L. Barker and David W. Marsden in districts that have teetered back and forth between parties.

Republicans, who are outpacing Democrats in recruiting and fundraising, need to pick up three seats to take control of the Senate, where Democrats hold a 22-18 majority.

If they succeed, it would be the second time since Reconstruction that Republicans held the governor’s mansion, House and Senate at the same time in Virginia.

In the 39th Senate District held by Barker, Scott Martin, an assistant dean and associate professor at George Mason University, faces constitutional lawyer Miller Baker in the GOP primary.

Martin, 47, who jumped into the race in March 2010, criticizes Baker for getting into the race late after not being involved in local Republican activities. Martin said he has helped GOP candidates in Northern Virginia for years, including then-Sen. Ken Cuccinelli II, Del. David B. Albo and former attorney general Jerry Kilgore, who ran for governor in 2005.

“I didn’t come out of nowhere,’’ he said.

Baker, 49, who heads the appellate practice of McDermott Will & Emery in Washington and worked on Capitol Hill and the Reagan Justice Department, said he decided to get into the race after last year’s congressional elections.

“We have serious problems. I’m a serious person,’’ he said. “This is my contribution.”

Baker said he differs from Martin in that he is focusing on economic development and finding ways the state can become less dependent on federal spending and contractors. He said he wants to lure companies to Virginia that have no contracts with the federal government by offering a climate with low taxes.

“If we don’t get this economy fixed, nothing else is going to matter,’’ he said. “It’s the single most important issue.”

Martin said he wants to help small businesses by phasing out the professional and occupational license tax known as the BPOL tax, and by providing more benefits to veterans. The longtime educator also wants to allow taxing entities, such as the Fairfax County Board of Supervisors, to run school finances instead of local school boards.

Martin said his job at George Mason University prohibits him from taking a salary for serving in the Senate — about $18,000 a year — while Baker will both benefit from the money and meeting potential clients for his law firm.

Baker denies that, saying his firm has no business interests in Richmond. “Nobody is in this for the money,’’ he said.

Baker has raised $157,563, which includes a $75,000 loan to himself, while Martin has raised $143,207, with $95,200 in loans, according to the Virginia Public Access Project, a nonpartisan tracker of money in politics.

Martin and Baker criticize Barker for voting to raise the gas tax, opposing a bill that prohibits requiring Virginians to purchase health-care insurance and failing to be transparent about his votes or his political party.

Barker said he had 20 bills signed into law this year, including those that expanded the number of people eligible to obtain a protective order, increased the state’s rainy day fund and mandated that state contractors participate in a federal program to root out illegal immigrants.

Barker, a health-care planner from Prince William County who helped draw the new boundaries for Senate districts during this year’s redistricting process, said the district has become slightly more Democratic leaning since he narrowly defeated Republican Sen. Jay O’Brien in 2007. Barker has raised $195,156. The district includes parts of Fairfax and Prince William counties and Alexandria.

In the 37th Senate District, which includes parts of Fairfax, Steve Hunt, a retired naval flight officer and former Fairfax school board member who ran for the seat before, faces Jason Flanary, chief operating officer of a Fairfax telemarketing firm, in the GOP primary.

Hunt, who narrowly lost to Marsden in a January 2010 special election for the seat that was once held by Cuccinelli, is gunning for a rematch, saying more swing voters will turn out this time. He said that as a result of redistricting he has represented more of the voters in his four years on the Fairfax County school board than Marsden has in his two years in the Senate.

“It’s going to be a tough race — it was a tough race last time,” Hunt said. “It’s one of the key races in the fight for who controls the state Senate.”

Flanary said he will bring a businessman’s eye to rethinking the state’s fiscal policy.

“Someone who’s run a business understands how to stretch dollars, how hard it is to earn a dollar and how easy it is for the government to take that dollar away,” he said.

Instead of arguing about more or less taxes and spending, Flanary, 32, said he would focus on how tax dollars are being spent through audits and reviews and legislation that pushes government agencies to spend more efficiently. He said he supports restricting the gas tax for use on road maintenance and setting aside some new money from revenue growth for transportation improvements.

Hunt, an analyst at a defense contractor, stressed that he has 15 years of private-sector experience, whereas most of Flanary’s career has been in lobbying — as vice president of government relations for the Virginia Chamber of Commerce and as the head of a tech association.

“I’m older and wiser enough to realize that just because I’ve been in one business doesn’t mean I can tell someone how to run a restaurant,” said Hunt, 53. “Jason is pretty much an unknown. . . . Issue-wise, what he says and what I say are very similar. It’s just that I’ve got a track record that shows where I’m coming from.”

Marsden said he thinks voters will recognize his record on education and transportation by reelecting him.

“You can do whatever kind of math you want, but I am the incumbent senator for the 37th District,” he said. “A state senator has a different set of duties than other elected officials, and I think I’ve done very well.”

Flanary raised $75,503 with $30,000 in loans while Hunt raised $37,340, including in-kind contributions, according to the VPAP.

The winner of the primary will face an uphill battle against Marsden, who has raised almost $200,000 in cash and in-kind donations, according to the VPAP.