Here's how the winning campaigns worked since 1988:
In 1988, the economy was doing well so the campaign centered on wedge issues - the Pledge of Allegiance, etc. Bush won by promising to continue Reagan's economic policies including no new taxes and by painting his opponent as being a typical tax and spend liberal.
In 1992, the economy was doing poorly. Clinton's winning campaign's motto was "It's the economy, stupid." Clinton painted Bush as being to out of touch to understand the economic issues facing typical Americans.
In 1996 Clinton was able to coast to reelection against Dole whose candidacy never caught on.
In 2000, Gore ran on a class warfare platform. He lost the election but won the popular vote.
In 2004, George W. Bush was able to paint his opponent as an out of touch rich guy.
The Obama campaign is using an "all of the above" strategy. They are trying hard to paint Romney as being rich and out of touch. They are also trying to remind us that he is "different". They also threw in some class warfare and some wedge issues.
To date, their approach is not working. Unlike Kerry who was born rich and married into money, Romney earned his fortune. Yes, his father was well-off by the time Romney went to high school but he worked his way up.
Attempts to remind us that Romney is "different" (code for Mormon) are doomed to failure. Romney may be from an exotic religion but he was raised in the country. Obama was raised in Indonesia by a Muslim step-father. That is why the "Obama ate dog" counter-attack was effective. No one really thinks that he acquired a taste for Lassie but it does remind us of how different Obama's upbringing was from most people's. Reminders that Romney's great-grandfather was a polygamist also flounder since the rejoinder is that Obama's grandfather was also a polygamist.
Gay marriage as a wedge issue also flopped. It helped Obama raise some campaign funds (or kept some contributors from closing their wallets) but more people are against it than for it.
Attacks on Bain Capitol are also risky since they let Romney talk about the jobs he created.
The class warfare (soak the rich) is more useful for energizing the base than for converting undecideds.
There are three modern campaigns that Obama cannot use as a model. His own 2008 campaign cannot be reproduced since he ran as a blank slate.
In 1980, Reagan won on the question, "Are you better off today than you were four years ago?" He repeated this in 1984 as part of his Morning in America campaign. The last thing Obama wants to do is remind people about the economy.
In the end, the Clinton campaign had it right - during an economic downturn it is all about the economy.