The CNN Election Timeline Tracker displays national CNN Poll of Poll results for presidential contenders Democrat Barack Obama and Republican John McCain. The CNN Poll of Polls are calculated using a variety of polling organizations including CNN/Opinion Research, Gallup, Mason-Dixon, Hotline/Diageo, Quinnipiac and Ipsos. Issue Tracker The CNN Election Issues Tracker displays the latest polling on what Americans say are the most important issues this year, including the economy, Iraq, health care, education, illegal immigration, homeland security, Iran, energy, and a range of other social, domestic and international issues.