Republican presidential contender Mitt Romney's growing presence in Virginia has re-energized the state's Republicans, who just months ago worried that the statewide campaign apparatus that President Obama was aggressively assembling there would give the Democratic incumbent an edge in a critical battleground state.

One hundred days out from the election, both Romney and Obama have dug in in Virginia, opening local campaign headquarters in swing districts and establishing massive coordinated campaigns with the state parties.

Romney, who had only a meager campaign presence in Virginia during the Republican primary, has made up significant ground since clinching his party's nomination in May.

With the opening of an office in Springfield on Saturday, the former Massachusetts governor now has 27 offices set up in the state, according to his website, most of them in the heavily populated crescent from Northern Virginia down to Hampton Roads.

Obama, who won Virginia in 2008, has 24 field offices set up in the state, also concentrated along the Northern Virginia-Hampton Roads crescent, with a few in outlying college towns. But Republicans believe Romney has closed the gap and will be competitive heading into the fall.

"You had Gov. Romney coming out of a bruising, yearlong primary. I think the campaign is in outstanding shape," said Gov. Bob McDonnell, who in May expressed concerns that Romney was losing the ground game to Obama. "It's not the number of buildings; it's the amount of people and the intensity, and I feel confident at this point we're tacking down ground superiority."

Virginia's 13 electoral college votes are seen as critical by both campaigns. The most recent Quinnipiac University poll showed Romney and Obama virtually tied in Virginia, but Republican voters are more enthused about the upcoming election than their Democratic counterparts.

Obama is working hard to turn out his own voters in the state. He'll return to Virginia on Thursday for his third campaign appearance there in less than a month. On Saturday, his campaign conducted one of its largest statewide get-out-the-vote efforts of the race.

"While the Romney campaign has finally decided to join the party by recently opening offices in Virginia, we've been busy for years building on our historic grassroots effort that propelled the president to victory in the commonwealth in 2008," said Marianne von Nordeck, spokeswoman for Obama's Virginia campaign.

Romney has leaned heavily on the campaign structure that McDonnell built during his gubernatorial run in 2009, and fine-tuned in 2010, when Virginia Republicans netted three new congressional seats. But he's also recruiting local Republican candidates to act as his campaign surrogates on their home turf.

"They're pulling us along. [The Romney campaign has] got a huge organization, and they're putting a big footprint here and they want to coordinate," said Patrick Murray, a Republican running against longtime Democratic Rep. Jim Moran in Northern Virginia. "They know we have a pretty good army of volunteers. That's how we get out the votes and contribute."