Can Obama recapture magic of 2008?

• John Avlon: Barack Obama launched his re-election bid Monday
• It will be difficult for the president to win as strongly as he did in 2008, he says
• A positive for Obama is the apparent weakness of the GOP field, he says
• Avlon: The electoral map has gotten more difficult for Obama and Democrats

Editor's note: John P. Avlon is a CNN contributor and senior political columnist for The Daily Beast. He is the author of "Wingnuts: How the Lunatic Fringe Is Hijacking America."

New York (CNN) -- President Obama officially kicked off his re-election campaign today with an early morning e-mail blast to supporters.

The campaign launch video featured interviews with supporters from across the country, carefully representing key demographics (youth, the elderly and Hispanics) and swing states (Nevada, Colorado, North Carolina). It communicates the president's strengths and weaknesses as he tries to recapture the magic of 2008 and turn it to a second term.

With the election still 20 months away, handicapping a presidential campaign is a tricky business, but already there are dynamics in place that will drive 2012.

First a flashback: In 2008, Obama won 28 states and 365 electoral votes, with the support of 90% of liberals, 60% of centrists and even 20% of conservatives. It's hard to believe that he'll be able to meet or exceed those numbers in 2012.

Obama's current job-approval rating is now evenly split with 46% approving and 46% disapproving, according to a new Gallup Poll.

He's proven to be more polarizing than advertised -- and it's never good to be below 50% -- but a look at history shows reason for some optimism at the White House. At this point in their terms, both presidents Reagan and Clinton had approval ratings below Obama's -- 41% and 44% respectively. Each went on to easy re-elections.

It's significant that Obama scores higher on his personal qualities than his policies. For example, a January CNN poll found that 60% of Americans said that Obama was "honest and trustworthy" even though just 47% said they "generally agree" with him on "issues they care about."

This gut-check likeability and trustworthiness can make all the difference in a presidential election -- even, and especially after, an epic "shellacking" like the 2010 midterms. That's why the campaign's first video has a late middle-aged white guy from North Carolina saying: "I don't agree with Obama on everything -- but I respect him and I trust him."

The economy is the greatest x-factor in any presidential election -- people vote their pocket-book. The economy is improving, but slowly, with unemployment now at 8.8% -- much higher in key presidential campaign states like Florida, Nevada and Michigan. The stock market hit its low on Day 50 of the Obama administration, but the president is still seen as anti-business by many on Wall Street -- while the far-left thinks he's a corporate sellout; welcome to our schizophrenic politics circa 2011).

One lingering weakness is the president's reluctance to speak to the middle class -- he didn't even say those words in his last State of the Union -- and American elections are won by the candidate who connects with moderates and the middle class.

To that end, Obama's campaign advisers need to keep the closest eye on independent voters. They voted for Obama by an 8 percentage point margin in 2008, but then supported Republicans in the 2010 midterms by double-digits. Currently, the president's job approval among independents is 41% according to the Gallup poll -- down from a high of 61% in late April of 2009.

But there are two dynamics that might matter more than any other in determining the outcome of 2012 -- one positive for the president and the other negative:

The weak Republican field: Elections are ultimately 'compared to what?' propositions -- and the elephant in the room for the GOP in 2012 is that they are putting forward a weak field. Most prospective candidates trail Obama in hypothetical head-to-head poll comparisons -- with the exception of my former boss Rudy Giuliani in a Harris Poll.

Because the Republican Party is increasingly conservative on both social and fiscal issues, the candidates who most excite the base -- like Mike Huckabee and Sarah Palin -- are political kryptonite in the general elections. Inversely, candidates who might have the best chance in a general election, like Indiana Gov. Mitch Daniels or outgoing former Utah Gov. John Huntsman, will have a hard time winning the primary. When fringe Congresswoman Michele Bachmann out raises front-runner Mitt Romney -- as she did last quarter -- it should be seen as a cry for help from the Party of Lincoln. The beneficiary of this clown car hyper-conservatism is President Obama.

Electoral map is tougher in 2012: This is the harshest reality-check for the re-election team. Obama is unlikely to win with a larger electoral margin than he did in 2008. States that narrowly swung his way in 2008 but have rarely voted Democrat since 1964 -- like Indiana, Virginia and North Carolina -- will be difficult if not impossible to all place in the Obama column this time.

Swing states like Ohio and Pennsylvania now have Republican governors -- while the Senate looks likely to be retaken by Republicans in 2012. Finally, the new census showed the biggest population growth in deep red states like Texas, Arizona, South Carolina and Georgia -- while the more liberal northeast lost population and therefore congressional seats and electoral votes.

Unless Obama can hold on to at least Florida, Ohio and Pennsylvania, his re-election prospects are dim. And that's one reason why newly elected Florida Sen. Marco Rubio is already being touted as a likely Republican VP nominee almost regardless of who is on top of the ticket.

The 2012 presidential race begins now. The fact that Obama has so far failed to build on his 2008 coalition is a significant hurdle to clear on his way to re-election. Reagan-Democrats carried the Gipper to a landslide re-election in 1984 -- there are few, if any, Obama-Republicans today.

Obama hopes to inoculate himself with an unprecedented billion-dollar campaign war chest while the Republicans try to find a candidate who can win both the nomination and the general election. It's a tall order on both sides of the aisle as the real life drama of presidential campaigns gets under way.

The opinions expressed in this commentary are solely those of John P. Avlon.