MASON, Ohio (AP) -- Romney-Ryan signs sit on nearly every block in this southwest Ohio suburb and there's scant trace of support for President Barack Obama.
Cynthia Herman is determined to find it.
She is among the Obama volunteers who have taken on a tough, but possibly decisive mission: wade through the grumpy responses, slammed doors or arguments in opposition territory to find backers of the president.
Trimming GOP margins in historically Republican areas helped Obama in 2008 in places such as Jacksonville in the Duval County area of northeastern Florida and in Republican-dominated counties in southwest Ohio, which delivered margins of more than 2-to-1 for George W. Bush and clinched his 2004 re-election. Obama also is also employing the behind-enemy-lines strategy in swing-voting states such as Colorado, where he has campaign operations in heavily Republican areas such as Colorado Springs.
Ohio is one of the most pivotal and closely contested battleground states, with most polls showing a very competitive race, and an Obama vote in a Republican stronghold like Mason County counts just as much as one in the Democratic bastion of Cleveland on Election Day next Tuesday.
Mitt Romney's campaign knows that arithmetic, too, and has made forays into Democratic northeastern Ohio. He's also campaigned in places such as Pueblo, Colo., where Democrats outnumber Republicans 2-to-1.
Romney's running mate, Paul Ryan, recently campaigned in Democratic areas of Ohio, visiting Youngstown, which Obama easily carried in 2008, and later going to Berea and Cleveland State University, in the Democratic bastion of Cuyahoga County. Romney has also repeatedly worked traditionally Democratic areas.
"Some of these counties are historically blue, but I don't think Democratic enthusiasm is on the rise there, it's on the wane," said Scott Jennings, Romney's Ohio campaign director. "If I can turn out my people and convince some of these conservative Democrats and independents, I can change the margins up there by a significant amount."
The Romney campaign doesn't have as extensive a network of field offices in Ohio as Obama's operation but says it is has expanded the '08 GOP presence and sees results when candidates campaign personally in Democratic regions.
"When you're in a heavily Democratic area, I think the Republican candidates have to go in there to let people know what they really stand for," said Gwen Conti, 67, a Democrat who went to Youngstown to see Ryan and plans to vote for Romney because she doesn't trust Obama. "Because all the advertisements you see on TV are all negative, and people don't really get to see the real person."
The three counties that form a crescent around Cincinnati -- Butler, Warren and Clermont -- are loaded with white conservative voters and bedroom communities. Obama did between 3 and 4 percentage points -- and 23,000 votes -- better than John Kerry did in 2004 in that area. He also won Cincinnati-based Hamilton County, the first Democratic presidential candidate to do so since Lyndon B. Johnson in 1964.
There are seven Obama field offices in the three Republican counties, up from three in 2008. One of the new offices is in Clermont County, where Obama snagged 33 percent of the 2008 vote without an office.
"I'm not saying Obama's going to win Clermont County, but I think we'll put a crack in it," said phone bank volunteer Gerry Myers, 71, in New Richmond, which lies southeast of Cincinnati on the Ohio River.
Another new Obama campaign office opened in Warren County, on Main Street in downtown Mason. It's in a converted book store and has a break room with a stocked refrigerator, a data room with rows of computers, a phone bank area and, on this day, stacks of warm breakfast burritos to fortify volunteers before they set out. In '08, volunteers here staged from a parking lot and used a Panera Bread restaurant for their phone bank.
Sally Gasior, a team leader at the Mason office, said Obama critics are usually polite in the suburban neighborhoods, but volunteers are taught to avoid arguments and leave quickly if confronted angrily. It's been decades since a Democrat carried the county, from commissioner to president.
"When we find supporters, sometimes they'll say 'I didn't know there were any Democrats in Warren County,'" she said. "They feel isolated, and they're happy to see us."
The campaign has been subjected to apparent pranks -- some people showed up at the Mason office saying they got phone calls telling them they should go there to sign anti-Obama petitions. And, about 10 miles up US-42, workers at the Warren County Democratic Party office in Lebanon arrived one recent morning to find someone had dumped a load of horse manure in their parking lot.
"I felt like Dorothy in the Land of Oz," volunteer Libby Rupp, a Democrat, recalled about moving here from Maryland a decade ago.
They know their work is uphill -- the Romney campaign showed its muscle Oct. 13 when it reported supporters knocked on 15,000 doors before Romney arrived in Lebanon for an afternoon rally. The Romney campaign predicts it will return Warren to '04 margins, when Bush won 72 percent of the vote.
Working from lists of people who have voted in a Democratic primary in the past or whose party affiliation is unknown, Herman knocked on dozens of doors on a fall afternoon. At one, no one answered, but barking dogs were let out to charge the fence.
Finally, she hit pay dirt in an upscale golf-course community.
Jennifer Harp, a mother of three who works in the finance industry, said she thinks Obama will do more to help the many economically struggling people in the country.
"I just don't approve of Romney," she said, admitting her husband and most neighbors disagree with her. "I'm in the minority in this neighborhood."
She got a warm handshake and thanks from Herman, a 57-year-old massage therapist and social worker, who made sure Harp had information on how to vote early.
"I like the challenge," Herman said, then headed off to her next address.
Associated Press writers Nicholas Riccardi in Denver and Kantele Franko in Youngstown, Ohio, contributed to this report.
Contact Dan Sewell at http://www.twitter.com/dansewell