The pundits all have their theories, and some of them may even have a grain of truth to them, such as the theory that he is simply trying to anger republicans to the point where they make a mistake, allowing Democrats to keep the White House in 2016. And I agree that Mr Obama probably does have that in mind. But there is an even more insidious nature to his plan.
The Democrat party has spent decades cultivating the Latino voting block, and they need it if they are to keep virtually perpetual control of the government. It is critically important to them. But with both houses of Congress going into the hands of Republicans in January, Obama sees a very real threat to the Democrat plan - Republicans could very easily pass an immigration bill, and leave Democrats holding an empty bag. I believe President Obama would rather have his presidency go down in flames, rather than to allow Republicans to win over the Latino voting block.
After all, if the Republican Congress passes an immigration bill - and they will - and Obama signs it, Republicans win. But if Obama vetoes it, Latinos will be so angry that Democrats would never get another Latino vote and the Republicans still win. In either case, the Democrats lose if Republicans are allowed the opportunity to pass an immigration bill.
So, Obama has a real need to act preemptively - to use an Executive Order to make Latinos believe the Democrats are looking out for them, and to do it before January.
And THAT is why he will act before the new Congress is seated. It has nothing to do with what is good for the country. With Mr Obama, it is always about what is good for the Democrat party - even to the detriment of the nation.