He should have flooded the airwaves in the summer with a combination of positive spots about his record and negative caricatures of the president. Romney allowed Obama to define him early, which became very difficult to overcome.
I also think he should have pushed hard for Susana Martinez to be his running mate. Ryan didn't really offer very much in the end. If Romney had basically kept Martinez in Nevada, Colorado, and Florida speaking Spanish for three months (plus a few trips into Ohio and Iowa touting her gun ownership), she could have moved the needle.
That being said, the race was winnable for Romney until roughly the second debate. If Romney and Obama had given the same performances in Round Two that they gave in Round One, Mitt Romney would now be the president, easily on track for a second term.
