Other than giving Romney a boost in Ohio, Portman's potential help to the ticket nationally is questionable.
"You have to be a really close observer of politics to know Rob Portman," said Merle Black, an Emory University political scientist. "He's someone who would have to be introduced to the rest of the country."
Portman says Romney has the upper hand on economic issues, from jobs to tackling the debt and deficits. He has cautioned Republicans not to get detoured by issues such as gay marriage, which he opposes.
"As Bill Clinton used to say, 'It's the economy, stupid,'" Portman said, sitting in his Chevrolet Silverado pickup truck during a recent campaign swing through his old House district, which runs along the border with Kentucky.
He shows off his Spanish and explains he learned it as a youth spending summers as a ranch hand in Texas, sleeping in bunkhouses with Mexican cowboys. "I know a lot of bad words," he said.
A prep-schooled Ivy Leaguer — he has a bachelor's from Dartmouth — who became worth millions through family businesses, practicing law and investments, Portman was dubbed "Prince Rob" by an opponent in his first congressional race in 1993. Strong support in the eastern Cincinnati suburbs lifted him to victory in the Republican primary with little help from rural voters, but he learned Appalachian lingo and worked on building connections in the economically struggling five counties to the east.
Far from the Washington Beltway, people say with pride they're in the Bible Belt. Portman fits in. He's a former Sunday school teacher, a supporter of local efforts to display the Ten Commandments in public places and an avid hunter.
During a stop at the at the 207-year-old Olde Wayside Inn on West Union's Main Street, Portman acted out for supporters gathered around dining tables how a friend slowly pointed the .20-gauge shotgun Portman lent him and then bagged a pheasant. The crowd chuckled.
"He's someone you can count on," said Ron Baker, a businessman in the Ohio River city of Portsmouth. "He's easy to talk to, and he listens."
To the Rev. Peterson Mingo, pastor of the Christ Temple Baptist Church in urban Cincinnati, Portman does things for people without seeking anything in return.
Mingo, an ex-con who's lost five brothers to violent crime, met Portman more than a decade ago when he questioned the then-congressman about the "Coalition for a Drug-Free Cincinnati" Portman had started. Portman invited him to join the coalition's board. What followed was years of brainstorming sessions, church visits, family picnics and favors. Portman arranged for buses from his own church to be used by Mingo's church to take youths to summer camp.
"He is real high on my list in terms of people I love and trust," Mingo said.
Friends who know Portman as a witty outdoorsman, a skilled and daring kayaker and adventurer who's paddled down the Rio Grande and China's Yangtze River are irked when he's described as "boring."
"I don't take it too seriously; maybe I should," Portman said of the label, then added an answer that fit the description. "I really try to focus on my job as a senator and doing the best I can."
Associated Press writer Andrew Taylor in Washington contributed to this report.
Dan Sewell can be contacted at http://www.twitter.com/dansewell
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