(CNN) - Beginning in May, a group called Iowans for Responsible Government spent over three quarters of a million dollars on television ads and mailers lumping Republican gubernatorial candidate Terry Branstad in with "liberal" politicians like President Obama, Nancy Pelosi and Bill Clinton.
Branstad at the time was engaged in a GOP primary fight against conservative activist Bob Vander Plaats, a race he won on June 8 by 10 points.
Citing Branstad's record on taxes when he last served as Iowa governor in the eighties and nineties, one mailer from the group blared: "Liberal Terry Branstad would make Bill Clinton, Barack Obama and Nancy Pelosi proud."
One mail piece portrayed Branstad in a lefty version of Mount Rushmore along with Obama, Clinton and Pelosi. Another claimed that Branstad and Obama both favor universal health care and "government mandates."
The mysterious group was headed by headed by former Iowa Democratic Party chairman Robert Tully, but the group refused to reveal its donors.
Now it turns out that the campaign casting Republican Branstad and national Democrats in an unfavorable light was funded by – surprise! - those very same national Democrats.
According to a disclosure report filed this week with the IRS, the group was funded entirely by the Democratic Governors Association, which is backing Gov. Chet Culver's re-election bid. The DGA spent $782,500 on the effort to rattle Branstad.
Branstad's campaign seized on the disclosure:
"A shadowy, out-of-state-funded group attempted to infiltrate the Republican primary for governor with distortions and smear tactics," said Branstad campaign manager Jeff Boeyink. "This is wrong, and despite their best efforts, Iowa voters were smarter than this and chose Terry Branstad as the Republican nominee."
The Democratic Governors Association did not respond to a request for comment.
UPDATE: The DGA defended the strategy.
"Terry Branstad saw which way the political winds were blowing and he knew his record of undisciplined and reckless spending would be vulnerable to an attack from the right," said DGA political director Ray Glendening. "He decided to repackage himself as a conservative in order to fit into the Tea Party movement.
"We saw an opportunity with this political hypocrisy and took advantage of it. Branstad continues to run a false and deceptive campaign, and he is not who he says he is. We have and will continue to expose the parts of his record that he would prefer to keep hidden."