SPRINGFIELD, Mo. (Reuters) - President Donald Trump said on Wednesday he still wants to see the U.S. corporate tax rate drop to 15 percent, saying cutting it is essential for the nation to regain its competitive edge. “We must reduce the tax rate on American businesses so they keep jobs in America, create jobs in America and compete for workers right here in America,” Trump said in a speech aimed at shoring up support for a broad tax-cut plan. “Ideally ... we would like to bring our business tax rate down to 15 percent,” he said. 