Energy companies, FBI agents, a media tycoon and even a candlemaker: Rudy Giuliani's firm has lobbied for them all and dozens more in Washington, opening the door to a wide range of potential conflicts of interest should he become president. If Giuliani were elected, his administration would be on the receiving end of regulatory requests, contract bids and policy proposals by the same clients of his Houston firm, Bracewell & Giuliani, that have contributed toward his personal net worth of millions of dollars. Although he has so far declined to identify all the companies with which Bracewell and his other...