In answer to the poster of this thread- answering without throwing in political postures.
At polling time today, it looks like the House of Representatives will have a Republican majority but the Democrats will probably keep the Senate by a slim majority.
If the Republicans see an advantage in blocking Obama's programs, likely there will be gridlock. By making Obama a 'lame duck', without ability to push programs forward, they would hope that voters would turn to the Republicans, who would then be able to push their programs forward and win the 2012 presidency.

Older line Republicans will use the noises of Tea-party types to their advantage, but the few elected will not have any weight in committees.

Obama has made some important gains. Along with other major nations, the stimulus packages and temporary buy-outs halted the descent into depression. Of course it will take time for jobs, income levels and hubris to return world-wide.
General Motors, etc., and major banking concerns are repaying loans as they get back on their feet.
The health bill, although too complicated, is quite an advance.
Involvement in the useless wars is being reduced although much too slowly.
Stimulus packages are helping in some areas.

Major failure- education for the future. Little hope of a turn-around under the Republicans if they gain control.