As Barack Obama appears more and more inevitable as the Democratic nominee, his lead over Hillary Clinton in Gallup’s daily tracking poll continues to widen. He now leads Clinton 55 percent to 39 percent in a survey conducted May 16-18. However, Obama isn’t yet getting much traction against John McCain, with only a 46 percent to 45 percent edge, within the 2 point margin of error of the May 14-18 survey. Clinton does a bit better, leading 48 percent to 44 percent.