As the presidential campaigns continue to ramp up their attacks (see: felon, liar, outsourcing), the candidates are homing in this week on the country's electoral fertile crescent.

President Obama held a town hall-style rally Monday in Cincinnati, and GOP candidate Mitt Romney is planning to head to Pennsylvania on Tuesday and follow the president to the Buckeye State on Wednesday.

While Pennsylvania remains an important Obama-leaning swing state, no state will be more crucial to a November victory than Ohio and its 18 electoral votes.

As he has in his previous forays to Ohio, including a two-day bus tour earlier this month, Obama characterized the voters there as the tiebreakers in what promises to be an exceedingly close race.

"The choice," Obama told the friendly, boisterous crowd at the Cincinnati Music Hall, "is up to you."

(Granted, Obama has been suggesting the same to non-Ohio voters. But the assertion resonates a bit more in this high-stakes state that tops almost every prognosticator's list — followed by Virginia, Pennsylvania and Florida — as the most likely to tip the election one way or the other.)

On Monday, Obama intensified his attacks on Romney's tax plan with a claim that it would create 800,000 jobs — overseas.

Seizing on an economist's analysis that a Romney-supported tax exemption on profits earned overseas by U.S. corporations would lead to a huge job shift overseas, Obama doubled down on his campaign's Romney-as-job-outsourcer claim:

"Today we found out there's a new study out by nonpartisan economists that says Gov. Romney's economic plan would, in fact, create 800,000 jobs. There's only one problem: The jobs wouldn't be in America."They'd be in other countries. By eliminating taxes on corporations' foreign income, Gov. Romney's plan would actually encourage companies to shift more of their operations to foreign tax havens, creating 800,000 jobs in those other countries."Now, this shouldn't be a surprise, because Gov. Romney's experience has been investing in what were called "pioneers" of the business of outsourcing. Now he wants to give more tax breaks to companies that are shipping jobs overseas."

The GOP response? That the analyst who wrote the report, Kimberly Clausing, is an Obama supporter and campaign contributor. And the president's own Export Council has also supported the so-called territorial tax system changes endorsed by Romney.

But Obama, who won Ohio in 2008 with just over 51 percent of the vote, drew applause and laughter from the receptive crowd in Hamilton County, the lone blue county in far southwest Ohio.

He asserted that government loans to the auto industry, which Romney opposed, saved that sector, which accounts for 1 in 8 jobs in Ohio. And he touted tax cuts during his administration that he says eased the tax burden of middle-class families by $3,600.

In 2008, Obama won the big-vote county, which borders Indiana and Kentucky, with 52 percent of the vote. He lost the three surrounding counties to GOP Sen. John McCain by big margins.

Republican George W. Bush won the state in 2000 and 2004. But in 2008, there was a 6-percentage-point swing toward the Democratic column. Obama ran about 2.6 percentage points ahead of where Kerry was in 2004, and McCain ran 3.6 points behind where Bush finished four years earlier.

This time around, the improving economic conditions in Ohio are expected to cut into Romney's argument that Obama has failed to revive the economy. The state's unemployment rate, which was as high as 10.6 percent in the last half of 2009, now sits at 7.3 percent. The national average is 8.2 percent. And local officials say manufacturing is returning to levels not seen in a decade.

And for months, Republican Gov. John Kasich has been touting the state's jobs recovery.

Between May 2011 and May 2012, the number of employees on nonfarm payrolls in Ohio increased by 75,700, according to seasonally adjusted numbers from the Bureau of Labor Statistics. That included 21,600 new manufacturing jobs.

Around the time Obama was speaking Monday, Kasich tweeted: "Good news for NE OH. Maines picked OH over MD for their expansion. That means new jobs and investment." Maines is a paper and food service company that broke ground Monday for an expansion in Ohio.

Romney no doubt hopes to use his forays into Pennsylvania and Ohio to change the current conversation about his time as a private equity capitalist and his reluctance to release a full complement of tax returns.

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