Republican frontrunner Mitt Romney highlighted the gap between himself and average Americans on Tuesday when he maintained he did not make “very much” from speaking fees, even though the $370,000 earned in a single year would be considered a fortune by many middle-class Americans.

His comments came at a press conference while out campaigning in South Carolina ahead of its potentially decisive primary on Saturday. Romney is the favourite to win in South Carolina, enjoying a double-digit poll lead over his nearest rival, former speaker Newt Gingrich.

At the press conference in Florence, he disclosed that he pays a tax rate of only 15% in spite of having an estimated wealth of $200m.

Romney has so far resisted offering details about his financial dealings but, during the presidential debate in Myrtle Beach on Monday night, he finally bowed to pressure and said he would “probably” release his tax returns in April.