President Barack Obama\'s administration on Wednesday unveiled plans to lower the top corporate tax rate to 28 percent and choke off lucrative loopholes, an election-year gambit testing Republicans\' pro-business credo. Doubling down on his pledge to build an economy based on \"fairness,\" Obama\'s lieutenants rolled out a plan that would lower the nominal business tax rate from 35 percent, but rake in more revenue by ending dozens of tax breaks and subsidies. The plan would lower taxes on manufacturing firms -- which would see a nominal 25 percent rate -- while introducing a minimum levy on foreign earnings which go largely untaxed today. The plan, which is in embryonic form, stands little chance of passing a divided Congress this year, but does present a political challenge to Republicans running for the White House. All of the candidates hoping to wrest the Oval Office from Obama in November have advocated even lower taxes for business, and are almost certain to oppose the measures. Treasury Secretary Timothy Geithner billed the reforms as essential to making the US economy more dynamic. \"In order to make us more competitive and create jobs here at home, we must reform our corporate tax code,\" Geithner said in a statement. \"The president\'s framework would boost growth and provide American companies with incentives to invest in the US while simplifying and cutting taxes for our small businesses.\"