Republican presidential hopeful Mitt Romney is calling for 20 percent across-the-board cuts in personal income tax rates as part of a program to help the economy grow.

Under the proposal, the top personal income tax rate would fall to 28 percent, according to a summary provided by Romney's campaign.

The current maximum is 35 percent.

Romney outlined parts of his plan in a campaign appearance Wednesday in Arizona, one of two states holding a primary next Tuesday. Michigan is the other.

Romney also said a new proposal the Obama administration outlined Wednesday to reduce corporate tax rates would actually increase taxes on businesses.

Romney, Rick Santorum, Newt Gingrich and Ron Paul meet tonight in the 20th debate of the campaign for the Republican presidential nomination.