Obama is a democrat. democrats go for centralisation of power. That is how they are.
They are a political party in many countries, which have parliamentary democracies.
But this party is designed to use the freedoms democracy offers also a party to destroy democracy and to grab for total power.

Examples: Obamacare and the following.

Police and Firefighter Monopoly Bargaining Passed the House

http://capwiz.com/nrtwc/issues/alert/?alertid=15218666&type=CO

The republicans are probably also eager for power and a threat for democracy. George Bush showed it.
Before the recent elections they promised to go against Obamacare and after them they wanted only take out the worst of it.
Are the chances better with them now?

My opinion is in the long run you need powerful organisations outside the government with the mandate to control it. These need the power to suspend, dismiss and punish
any member of parilament to uphold human rights and democracy and go against corruption within it.