Next Pew looked at how we answer that question based on our politics. The most conservative are most likely to agree that America is the greatest nation on earth. At the other end of the spectrum the most liberal are most likely to disagree with the statement. Across the board 38% of all Americans say America is the greatest, 53% say we are among the world's great nations, and 8% say there are other nations greater than America.
We may be talking about apples and oranges. Single issue voters will only vote for candidates who agree with them on that issue. For these voters their issue is a litmus test.
Categorically, we know that all voters are not single issue voters. For insight I visited an article published by the famous Pollsters at Gallup. In an article written about single issue voters in the race between Kerry and Bush, I found the example I was looking for. The article was written by Lydia Saad, a senior Gallup Poll Editor. You can find the entire article online at http://www.gallup.com/poll/13786/abortion-issue-guides-one-five-voters.aspx.