What's happening in this election cycle is the typical ebb and flow of good news and bad news for both candidates.
Obama had a very good winter and early Spring. The jobs numbers were great and the GOP sideshow made him look Godly by comparison. Then Romney secured the nomination, the jobs reports got weaker, and Obama said a few dumb things.
This actually parallels what has happened in many previous presidential elections. The summer seems to be typically bad for the incumbent or favored candidate.
Remember in 2008 Obama only had a slim lead against McCain and actually trailed him for a bit after the Republican convention. A CNN poll from June 2008 showed them neck and neck
I just stumbled upon a Fox News poll from June 2004 that showed Kerry leading Bush by 2 points
A CNN poll from June 2000 showed Bush leading Gore 50 to 38!
So it appears that the incumbent or favored candidate always seems to slip in the summer. I really don't know why but the pattern is there. We all know what happened in 2008. Bush took the lead in fall 2004 and Gore came from behind in the fall and won the popular vote.
My guess is that by the summer, the challenger is in full campaign mode, while the incumbent who is already in office (whether it's Obama, Bush or Gore) can't campaign at the same magnitude. But then by the fall, the incumbent comes out in full force and changes the dynamics.
Please people, save your grand predictions for the fall. The ball game hasn't even started.
http://articles.cnn.com/2008-06-05/politics/campaign.wrap_1_obama-mccain-money-from-federal-lobbyists-barack-obama?_s=PM:POLITICS
http://articles.cnn.com/2000-06-26/politics/cnn.poll_1_al-gore-sampling-error-george-w-bush?_s=PM:ALLPOLITICS
http://www.foxnews.com/story/0,2933,122378,00.html
With Kerry, I think he actually could have beaten Bush with a few more votes in Ohio. I think if he selected General Clark as his VP, he would have been able to get more military voters; and also defend himself against those vietnam swift boat attacks. But Bush was also a mediocre candidate, who did just enough to win.
I think there are a lot of things about Obama that are mediocre. I think that Romney has a strong opening. I think that if Romney picks a good VP and a strong VP he can make up the difference and beat Obama.
Its going to be a very close election that will be decided by Ohio and Virginia. More than anything, it will be how main street voters in those states perceive the election.