Do we need an independent prosecutor for ACORN?

Chicago polisci prof Charles Lipson makes the argument:

Independent prosecutors should not be appointed lightly. But in this case, there are good reasons why Atty. Gen. Eric Holder and other political appointees in the Justice Department should step aside. First, although no allegations have yet touched the Obama campaign, ACORN did have significant ties to the campaign and other progressive causes. Published reports show that ACORN and its subsidiaries received some $800,000 from the Obama campaign to get out the vote. Second, ACORN is intimately tied to the Service Employees International Union, one of President Barack Obama's most powerful and vocal supporters.

ACORN's close ties to the progressive movement and Democratic Party mean that there will be little public confidence if Holder decides not to pursue an ambitious investigation and ultimately prosecute....

What we have seen on tape cries out for a serious, independent investigation to determine if ACORN and its affiliates are a criminal enterprise, whether they have spent federal grants lawfully, whether they helped taxpayers file fraudulent returns, and whether they violated laws prohibiting tax-exempt organizations from engaging in partisan politics. These are big questions, and the public needs to know that Washington's answers are fair and impartial.