The presidential battle is on in Virginia, and the fight is serving local television networks handsomely.

Republican John McCain and Democrat Barack Obama are pouring advertising dollars into three Roanoke-based television stations that cover the Roanoke Valley and parts of Central and Southwest Virginia.

Traditionally a Republican stronghold, Virginia is considered a battleground state that could go to either party in this year's presidential election.

Armed with advertising dollars to spend, Obama appears to be taking the most advantage of Virginia's swing status. Since June, the Illinois senator has purchased more than twice the number of local television ads than McCain.

At three Roanoke-based television stations, Obama's campaign has doled out $695,461 for advertising since June. Those networks are CBS affiliate WDBJ (Channel 7), NBC affiliate WSLS (Channel 10), and Fox/CW affiliates WXFR (Channel 21/27) and WWCW (Channel 5).

McCain and the Republican National Committee have spent significantly less -- approximately $283,007 -- for advertising through the same Roanoke television stations.

Statewide, the spending picture is more of the same.

Obama spent about $2 million on Virginia television ads during the week of Sept. 28 to Oct. 4, according to the Wisconsin Advertising Project at the University of Wisconsin-Madison, which tracks political advertising. For the same period, McCain spent $547,000 in Virginia.

The Federal Communications Commission requires that satellite television broadcasters make political advertising files public.

The Roanoke Times would not comment on how much the presidential candidates have spent on newspaper advertising. The FCC requirements do not apply to newspapers.

Candidates more often are focusing on local ad slots, rather than purchasing national ad time. In a rare move, however, Obama is buying a 30-minute ad slot for national prime time television that will air on CBS and NBC six days before the election.

Advertisement spending is strategically focused. A campaign's advertising budget, and whether a specific region is necessary for winning votes, are the factors that drive ad spending.

Instead of McCain focusing on Southwest Virginia, where a survey by Mason-Dixon Polling & Research last revealed that he leads Obama, McCain is pouring his energy into Hampton Roads, where he plans to visit today. It's a hotly contested area of the state for both candidates.

And as for Obama's elevated spending in Central and Southwest Virginia, "where you are weak, you spend more money," said Bob Denton, a professor of political communications at Virginia Tech.

"Obama wants to try to keep as many states in play as he can. He has the money to do so."

Obama is the first major party candidate to decline public financing in the general election, leaving him free to spend as much as he can raise.

McCain, on the other hand, is limited to spending only the $84 million in public funds he accepted to cover all his costs in September and October. He's also getting help from the RNC, which raised $66 million in September.

It's been a long time since the region saw significant presidential campaign advertisements, because 1964 was the last year that Virginia voted for a Democrat for president. That was Lyndon Johnson.

"If the two campaigns had decided that Virginia was in the bag for any one candidate, we'd be closer to that zero number," said Jeffrey Marks, president and general manager of WDBJ.

Like many stations, WDBJ budgeted a year ago for the presidential election. Advertising expenditures can be "highly volatile," making sales difficult to predict, Marks said.

Political ads make up less than 10 percent of the network's yearly sales, he said.

WSLS has received an unexpected 50 percent boost in presidential advertising sales above its planned budget for the year, said Warren Fiihr, general manager for the station.

"The advertising is stronger than we anticipated," he said. Political ad sales generally make up 7 percent to 8 percent of the station's annual revenue.

Evidence that Obama is blanketing local networks with ads also is showing up in the kinds of advertising slots that his campaign has purchased.

At Fox 21/27 and CW5, Obama has purchased ad space for many daytime slots and sports programming, which generally are uncommon segments for political advertising, said Ralph Claussen, general sales manager.

"Obama is more aggressive in this area" than McCain, Claussen said.

At Fox 21/27 and CW5, Obama's advertising expenditures are more than double what McCain has spent since June.

Through Nov. 4, expect the number of presidential campaign television ads to build.

Both campaigns have aired more negative ads than candidates during the 2004 presidential election, according to the Wisconsin Advertising Project.

From Sept. 28 to Oct. 4, according to the project's findings, nearly 100 percent of McCain campaign ads were negative, compared with 34 percent of those by Obama's campaign.

"Attack ads," used to convince people not to vote for an opponent, typically are the last alternative if a political race is tight, Denton said.

"Attack ads have more impact than positive bio ads," he said.

The Associated Press contributed to this report.