PELLA, Iowa (AP) — Republicans competing for the chance to challenge President Barack Obama's re-election are casting him as a roadblock to economic revival while promising to resuscitate the U.S. manufacturing base.Several of the GOP contenders pitched their economic plans at an Iowa forum Tuesday, and criticized Obama's stewardship of the struggling economy.Rep. Michele Bachmann of Minnesota says "we need the federal government to get off our back." Former Sen. Rick Santorum says Democrats' health care law is standing in the way of businesses and is pledging to repeal it.And former House Speaker Newt Gingrich says Obama is simply "a left-wing radical" whose administration's regulations are crippling the business community..Former Massachusetts Gov. Mitt Romney and Georgia businessman Herman Cain skipped the event.