Government watchdog group Judicial Watch has obtained documents that show the Internal Revenue Service used donor lists from conservative tax-exempt organizations to determine who it would target for audits.

The IRS produced the documents in a Freedom of Information Act lawsuit filed by the group.

"These documents that we had to force out of the IRS prove that the agency used donor lists to audit supporters of organizations engaged in First Amendment-protected lawful political speech," Judicial Watch President Tom Fitton said. 

In a letter sent on Sept. 28, 2010, then-Democrat Senate Finance Committee Chairman Max Baucus of Montana wrote to then-IRS Commissioner Douglas Shulman: "I request that you and your agency survey major 501(c)(4), (c)(5) and (c)(6) organizations."

Shulman responded on Feb. 17, 2011, saying, "In the work plan of the Exempt Organizations Division, we announced that beginning in FY2011, we are increasing our focus on section 501(c)(4), (5) and (6) organizations."

IRS officials specifically targeted the U.S. Chamber of Commerce, a business-oriented lobbying group, for possible "high scrutiny," Judicial Watch said.

"The U.S. Chamber of Commerce is a 501(c)(6) organization and may find itself under high scrutiny," read an email sent on May 13, 2011 from an IRS official, whose name is redacted, to IRS attorney Lorraine Gardner. "One can only hope."

The IRS considered levying a 35 percent gift tax on contributions to 501(c)(4) groups that had donations in excess of $13,000. However, because the IRS had not enforced the gift tax since the Supreme Court ruled in 1982 that such taxes violated the First Amendment right to free speech, many in the agency considered a gift tax to be out of the question.

However, the IRS went on to audit at least five donors of an unnamed organization in February 2011, said Judicial Watch.

One organization specifically targeted for the gift tax was the super PAC, Crossroads GPS, which has ties to former President George W. Bush's senior political adviser, Karl Rove, according to internal emails.

"And the snarky comments about the U.S. Chamber of Commerce and the obsession with Karl Rove's Crossroads GPS show that the IRS was targeting critics of the Obama administration.  President Obama may want to continue to lie about his IRS scandal," Fitton said. "These documents tell the truth - his IRS hated conservatives and was willing to illegally tax and audit citizens to shut down opposition to Barack Obama's policies and reelection."

A new Government Accountability Office report released on Thursday says lax oversight at the IRS increases the risk that agents could continue to target tax-exempt groups based on their political, religious or educational views, the Associated Press reported.