President Obama on Wednesday plans to propose a major overhaul of the nation’s corporate tax code, an election-year gambit that is likely to draw a contrast over a key policy issue with the Republicans vying to replace him.

Obama will propose lowering the nation’s tax rate to 28 percent. At the same time, however, he will seek to increase the amount of revenues raised overall through corporate taxation by eliminating numerous deductions and loopholes that save companies tens of billions of dollars a year on their tax bills, according to a senior administration official.