There are several things to mention here. First, this should surprise no one. President Obama has embarked on the boldest liberal agenda possibly in history and second only to FDR, if second at all. Everything that President Obama has so far proposed domestically is a liberal's dream and a conservative's nightmare. From his budget, to universal health care, to cap and trade, to centralized educational planning, to a new regulatory framework, this is all boiler plate liberal causes. Of course, he is extremely polarizing.
On its own, this is not necessarily a bad thing. Here is how Jay Cost describes polarization.
Additionally, I don't think polarization is necessarily a bad thing. Polarization - as I see it - is where you have small differences within each party, but big differences between the parties. One beneficial consequence of such a situation is that the public, which is not really paying careful attention, stands a better chance of perceiving real differences between the two sides. Ultimately, that can make electoral results more meaningful - as a vote for a party can be better identified with a vote for a governing philosophy.
So, with no context, polarization is not that terribly awful. Where this polarization will likely become an albatross around Obama is that his main theme in running for president was an end to exactly this kind of polarization. We were supposed to get past partisanship, polarization, and politics as usual. Instead, we have been treated to a more intense version of politics as usual.
Candidate Obama never actually told anyone how he was going to accomplish any of this. Then, he became president. Immediately, he let Nancy Pelosi and Harry Reid write a massive stimulus bill. Republicans weren't consulted. It was hammered out near midnight and voted on by noon the next day. Even though only three Republicans supported the bill from either chamber, President Obama didn't demand that anyone go back to work to craft something both sides could agree on. Then, he moved immediately to create a budget that would massively increase the size of government. This is NOT post partisanship.
Furthermore, this is an opening that Republicans must drive a Mack truck through come both November of 2010 and eventually November of 2012. President Obama's policies are significantly less popular than President Obama. As such, if he is defined by his policies, then he will have a tough time. If he is defined by his policies, it will take very little skill to define him as a typical tax and spend liberal. By attacking the central theme of his campaign, the Republicans attack a central theme of his attraction. People were attracted to post partisanship and an end to politics as usual. Of course, we've had none of that, and Republicans must make the voters aware of it at the right time.