Voters across Virginia will cast ballots Tuesday to elect party nominees in local and legislative races.

Of the 16 legislative primaries across the state, nine will take place in Northern Virginia — six for state Senate and three for the House of Delegates — that will help determine whether Republicans will make gains in the November elections.

Voters in Arlington, Fairfax and Prince William counties also will vote in local races.

Polls are open from 6 a.m. to 7 p.m. Party officials expect low turnout during an election that falls in prime vacation season in an off-year when no federal or statewide candidates are on the ballot.

The Senate races include a pair of Democratic-leaning districts that are open because of the retirements of longtime legislators: Sen. Mary Margaret Whipple (D-Arlington) and Sen. Patricia S. Ticer (D-Alexandria). Arlington County Board member Barbara A. Favola, and lawyer Jaime Areizaga-Soto are battling to replace Whipple in one of the most negative races of the season.

Four other senate primaries are among Republicans, including the hard-fought race between Jeff Fredrick, former chairman of the Republican Party of Virginia and former delegate, and Tito Munoz, a small business owner and conservative radio host.

Two of the House races are in new districts centered in the growing counties of Loudoun and Prince William. A third House race, in one of the most solidly Democratic districts in the state, might be decided Tuesday unless a Republican or third-party candidate jumps in at the last minute.

The General Assembly drew new maps this summer to bring the 140 districts of the Democratic-controlled Senate and Republican-held House into alignment with population shifts detailed in the 2010 Census. The plans give Northern Virginia a new senator and three new delegates, all in the region’s growing outer suburbs.

Republicans are in a fierce battle to take control of the Senate, where Democrats hold a fragile 22-to-18 majority, and hope to pick up a handful of seats in the GOP-led House.

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