Two Republican presidential rivals are mixing it up over their competing tax plans. During an appearance in New Hampshire, Arizona Senator John McCain said Bush’s tax plan gives too much to the wealthiest 10 percent of Americans — and would burn up the entire federal budget surplus. McCain would use 70 percent of the excess federal tax money to fix the Social Security and Medicare systems. During an interview with Radio Iowa, Bush said his tax plan returns money to Americans — rather than keeping it in Washington to be spent.Bush said there’s a “tax gap” between McCain and himself. When asked about McCain’s potential challenge here in Iowa, Bush dismissed McCain as any sort of competition in the state. He says his record of leadership is different from someone in the legislative branch. Bush says he can’t imagine Iowans will want to vote for someone who doesn’t even visit the state. McCain decided to forego campaigning in Iowa, but appeared at a debate in Des Moines in December and will participate in the Republican candidates debate here on January 15. Bush campaigned in Davenport, Des Moines and Cedar Rapids yesterday.Bush is among several candidates treking across the state in the few days which remain before Iowa’s Caucuses. During a stop in Manchester yesterday, republican presidential hopeful Gary Bauer noted the field of G-O-P candidates has dramatically narrowed since it all began.Republican candidate Orrin Hatch campaigned in Fort Dodge, Boone and Perry yesterday.