Division on tax policy provides an opportunity for a clustered field of Republican presidential candidates, who often sound identical on social and economic issues, to differentiate themselves.

During his recent swing through the Midwest, President Barack Obama urged Congress to extend a temporary payroll-tax break that allows the average American worker to keep $1,000 of a $50,000 salary rather than paying that money in taxes. Obama wants to extend for another 12 months the 2-percent tax cut that became effective on January 1.

Both Texas U.S. Representative Ron Paul and former U.S. House Speaker Newt Gingrich agree with the extension, their campaigns confirmed to IowaPolitics.com last week. They support keeping the tax on workers' wages at a 4.2-percent rate, rather than the normal 6.2 percent rate, as a way to keep more money in the pockets of middle-income Americans.

But former Massachusetts Governor Mitt Romney and Minnesota U.S. Representative Michele Bachmann approach the payroll-tax cut differently, with an eye toward job creation, deficit reduction, and businesses.