By Greg Giroux, CQ Staff

To become president, Barack Obama will obviously have to win some states lost in 2004 by John Kerry , whose 251 electoral votes were a scant 19 short of what is needed. With its cache of 13 electoral votes, Virginia could go most of the way toward closing that gap, and Obama is going after them. His first big rally after Hillary Rodham Clinton conceded in June was staged in the Northern Virginia suburbs of Washington, where changing demographics give Democrats hope of swinging the state their way this fall.

Not long ago, such a bid might have seemed like so much political happy talk, or a feint aimed at getting the GOP to spend money playing unnecessary defense. Virginia is, after all, one of 11 states that have backed Republicans in each of the past 10 presidential elections, and it has the most electoral votes of that group. But even though George W. Bush twice carried the state by 8 percentage points, the Democrats have eroded the GOP’s dominance this decade. The party has won the last two gubernatorial elections: Mark Warner in 2001 and Tim Kaine — an early Obama supporter who made the vice presidential short list this summer — in 2005. Democrats won one Senate race two years ago when Jim Webb unseated George Allen after one term. And Mark Warner — tapped to keynote the party’s national convention — is strongly favored to pick up the other seat this fall when Republican John W. Warner steps aside after 30 years.

To win, Democrats will try to maximize turnout in Northern Virginia, and with Obama as the first black presidential nominee of a major party, they are also hoping for higher-than-average turnout among African-Americans, who make up 20 percent of the population. Republican strategists acknowledge that Obama will run well in Northern Virginia, although they say John McCain ’s image as an independent-minded Republican will limit the Democratic margin. The GOP is also counting on McCain’s history as a Vietnam prisoner of war and defense-focused lawmaker to appeal to the large numbers of military-related voters in Northern Virginia and the Hampton Roads area, including Virginia Beach. They expect him to do as well as previous nominees in Republican strongholds in the Shenandoah Valley and some suburbs of Richmond.

Although Obama cruised to victory in the primary, the result also exposed a potential weakness for the general election. He lost decisively to Clinton in southwestern Virginia, a mountainous area with many lower-income white voters who are ancestrally Democratic but socially conservative. He did poorly even with the endorsement of Rep. Rick Boucher , a pro-gun, economically populist Democrat who has represented the area since 1983.

While Obama faces a tough road, Mark Warner can practically put his name on the Senate seat. Warner (unrelated to the retiring incumbent) remained popular through the single term the state permits its governors. His Republican opponent, James S. Gilmore III, was also his gubernatorial predecessor, and Gilmore wasn’t so popular running the state. Gilmore also made a run for the presidency this year that was essentially over before it started. He badly trails Warner in surveys and in fundraising. A Warner victory would give the state two Democratic senators for the first time since 1970.

Democrats are hopeful that they will increase their numbers in the state’s House delegation, which has been 8-3 Republican since a GOP-drawn district map was implemented for this decade. The party is favored to pick up the suburban Washington seat opened by the retirement of Republican Thomas M. Davis III after seven terms. Democratic candidate Gerry Connolly is chairman of the board of supervisors in Fairfax County, where most district residents live. He faces a tough fight from Republican Keith Fimian, the founder of a home inspection company who is not well-known but is well-financed.

Of three Democrats with long shots at unseating GOP incumbents, the one with the best chance is Glenn Nye, a political newcomer with a background in international affairs that took him to global hot spots such as Iraq and Afghanistan. He’s challenging Thelma Drake , who in two terms hasn’t locked up the district dominated by Virginia Beach.

Tom Perriello, a Yale-educated lawyer who has founded some nonprofit organizations, is working to unseat Republican Virgil H. Goode Jr. , who for six terms has represented a swath of south-central Virginia where the liberal leanings of the Charlottesville area usually are outweighed by predominantly conservative turf toward the North Carolina line.

Judy Feder, a former Georgetown University dean, is in a rematch with 28-year veteran Republican Frank R. Wolf in a district that covers part of Fairfax and all of fast-growing Loudoun County.