Barack Obama represented ACORN in a successful lawsuit alongside the U.S. Department of Justice against the state of Illinois to force state compliance with a federal voting access law.

This lawsuit occurred in 1995, with Obama working alongside the US Dept of Justice in support of ACORN. I don't think this qualifies as indicating support or any recent ties to ACORN. That was my previous point, MCCain indicated support for ACORN far more recently than Obama, although I don't really think either has any voter tie frauds worth mentioning other than by those attempting a smear campaign.