I don't think Romney ran the worst campaign. But Goldwater & McGovern never had a shot at winning.
So I think a better question is: Did Romney run the worst campaign of a candidate who could have won?
To which I say no, Dukakis was worse then Romney.
I don't think there's any way Dukakis could've won. How far back should we look at?
Dukakis is the answer to the worst modern Presidential campaign. He had a double digit lead in the polls at various points, but his campaign was a trainwreck. The Dukakis campaign manager had actually never run a political campaign before and it showed. They refused to respond to attacks by Bush and they made a ton of rookie mistakes.