Romney:
1) Willingness to lie his ass off. I would say that this is more than a willingness, it is an eagerness. Romney will literally say anything to get elected. This can work against him in some ways, but it is certainly something that the GOP’s spin doctors can work with. (See strength #2)
2) Access to billions of dollars. Not just his own, but thanks to ‘Citizens United’ he and his surrogats can pour previously unheard of cash in to this campaign. [ Money + Willingness to outright lie = momentum.] The coarse mathmatics of negative campaigning works in an underdogs favor. He can put the President on the defensive, and minimize his strengths.
3) He is the underdog. The press loves a horse race, so the fact that he is currently trailing in the polls turns every story into a “comeback kid” story. It gives the lazy media a dramatic arc.
4) “He looks Presidential.” I’m pretty sure when Republicans say this they mean, “He is white.” When the media repeats it, they are talking about the fact that he looks like Presidents used to look in movies before they started to be played by Morgan Freeman.
Obama:
1) Obama is the President of the United States. There are simply a lot of advantages that accrue to the incumbent. I’m not exactly sure what they are, but how else can anyone explain George Bush being re-elected?
2) Obama gets to run against a Republican and Republicanism in general. Republicans are deeply unpopular and have been hard at work trying to be less popular with each passing day. The Republican primary contest, George W. Bush, and the Republican Congress provide the President’s team with mountains of evidence that Republicans need to be kept as far away from the levers of power as possible.
3) The President is popular. This reality escapes Republicans who are absolutly convinced that Obama is the most hated person in America. (They keep saying it to each other so it must be true. That’s how “truth” works on the GOP side.)
4) Obama is 1-0 vs. Republicans in Presidential elections. Team Obama knows how to win. Granted his last win was against a weak John McCain who flubbed his first leadership test by picking and idiot for a running mate, but there is something to be said for having been in the big dance. There will be gaffes and goofs on both sides over the next seven months, and team Obama knows how to minimize theirs while maxing out their opponents.