Washington Post: Four-dollar-a-gallon gas has done something that few Republicans thought possible just a few months ago: given them hope. United behind a renewed push for offshore oil drilling, Republican members of Congress and the party’s presumptive presidential nominee, Sen. John McCain, think they have found their best political issue of the 2008 campaign. McCain strategists and GOP leaders on Capitol Hill say the issue, which polls suggest Americans favor by healthy margins, lets …