The 2008 U.S. presidential election was the first in 12 years in which large numbers of Americans did not believe the result was unfairly influenced by the machinations of politically biased state election officials. But it was also the first in a dozen years that was not close, as Democrat Barack Obama cruised to a blowout victory over Republican John McCain.

With 2012 shaping up to be another tight contest, experts say controversy is likely this year, especially given that 33 of the 50 state election authorities are led by partisan politicians, who are free to work for candidates’ campaigns. 

“People don’t pay attention to problems of partisanship until it’s too late,” said Richard Hasen, an elections law specialist at the University of California-Irvine.

There has already been election controversy this year. Republicans and Democrats have been fighting for months over voter identification laws that Republicans say are necessary to prevent fraud, and Democrats contend are efforts to make it harder for poorer voters and members of minorities – who tend to vote Democratic – to cast ballots.

In Florida, election officials appointed by the state’s Republican governor are in a fight with the Department of Justice over their effort to purge the voter rolls of non-citizens, an effort federal authorities contend unfairly targets members of minority groups.