RALEIGH, N.C. — After spending $56 million on a TV advertising barrage unprecedented in North Carolina political history, the presidential campaigns of Barack Obama and Mitt Romney are preparing for a two-month sprint for the state’s 15 electoral votes.

So far neither the summerlong TV advertising blitz, nor the Democratic convention in Charlotte have moved the needle on public opinion. Most polls show the state closely divided between Obama and Romney today, just as it was in June.

The campaigns are expected to focus on making sure their supporters get to the polls, and go after that sliver of undecided voters – perhaps as little as 5 percent.

Democrats are courting white women suburbanites who may be uncomfortable with some of the Republican positions on social issues. Republicans are wooing conservative rural and small-town Democrats in the eastern and western parts of the state who may not like the direction their party has gone.

North Carolina has traditionally been a red state, but surprised many by voting for Obama in 2008 by 14,000 votes. North Carolina has long been viewed as the most difficult for Obama to win of the nine or 10 key battleground states.

The Romney campaign this week began suggesting that Obama was cutting back on its advertising in North Carolina, preparing, for what its pollster Neil Newhouse, a Duke graduate, called “a stealth withdrawal.”

“I think you are seeing that the Obama campaign is recognizing that this is still functionally a Republican state and it is going to be voting in big numbers for Gov. Romney,” Rich Beeson, Romney’s political director said in an interview Tuesday. “I think what you are beginning to see is they are beginning to make a tactical withdrawal from the state.”

Beeson said in June, the Obama campaign was spending the same amount in North Carolina as in Iowa. By August, the Obama campaign was spending twice as much on TV in Iowa as it was in North Carolina.

The Obama campaign scoffed at the assertion, saying any reduction of TV advertising was centered on the Democratic Convention in Charlotte.

Mitch Stewart, Obama’s Battleground States director, said the campaign will remain in North Carolina for the duration. Stewart was in Raleigh Tuesday for a training effort for campaign workers.

“Unlike the Romney campaign, which is competing on a shrinking map, we are in North Carolina to stay and will continue to grow our organization across the state as we have since 2008,” said Obama campaign spokesman Ben LaBolt.

In only three states – Florida, Ohio and Virginia – has more money been spent on TV advertising in this presidential election than in North Carolina. And the residents in those other states may not actually have seen more ads than Tar Heels because they are larger states with more expensive media markets.

In most major battleground states, Obama and Romney are fairly even in TV advertising. But in North Carolina, the pro-Romney forces have a substantial edge, outspending the Obama forces $34.5 million to $21.9 million, according to NBC News and SMG Delta, an ad tracking firm.

“That is simply what you would expect,” said Carter Wrenn, a veteran GOP consultant, who ran Steve Forbes’ presidential campaign.

“Obama can win the nomination without North Carolina,” Wrenn said. “There is really not a path that Romney can win without North Carolina. My guess is, he’s looking at it and saying, ‘I got to have it.’ And so they are putting more into it. Obama is looking at it and saying, ‘I’d like to have it, and I don’t want to write it off, but I’d really rather have Florida or Ohio.’ ”

For the next two months, much of both campaigns’ effort will be centered on turning out the vote.

The Obama campaign said it has 50 offices set up in the state and has a comparable number of staffers to what it had in 2008 (when it had 400 paid staffers). Campaign officials said they do not expect TV advertising to slack off.

The Obama campaign said it has registered more voters in North Carolina than in any other battleground state. The Romney campaign counters that Obama is losing support among 18- to 29-year-olds and that registration of Democrats is down in the state from 2008. The number of registered Republicans has also decreased while the number of voters registered as independent has shot up.

The Romney campaign has 20 offices set up.

“Clearly we have a very solid organization,” Beeson said, “where in 2008 we were caught flat-footed and we were resolved to make sure that didn’t happen again and it hasn’t.”

Staff writer John Frank contributed to this report