The elections may help settle deeply rooted political feuds or they could rekindle rivalries with renewed violence.
In the months after the January vote, U.S. troops are expected to start drawing down in significant numbers, further testing the still-fragile stability that has prevailed for the past year.
And by December, Iraqis are scheduled to vote for a new national government.
How many of the 150,487 troops currently in Iraq will remain on the ground by then depends on how far and how fast Obama decides to implement his election pledge to withdraw troops within 16 months.