(CNN) – The Democratic Senatorial Campaign Committee responded Friday to a scathing letter from a top executive at Koch Industries, Inc., who blasted the group after he was solicited for campaign contributions.
Philip Ellender, president for government and public affairs at Koch Industries, a frequent Democratic target, said he received a letter and voicemail from DSCC Chair Patty Murray in June. He posted the audio from the voicemail on KochFacts.com, a website dedicated to defending the influential conservative Koch brothers - David and Charles.
In a letter obtained by CNN, DSCC Executive Director Guy Cecil wrote to Ellender, saying the "form letter" and follow-up solicitation were a staff error.
"However, the bigger and more troubling mistake is the long political history of your employer, the Koch Brothers," Cecil wrote in the letter. "If you'd like to share voicemails from all the shady groups asking you for millions of dollars, we'd happily listen to those as well."
"So, I write to make it clear that your invitation was an error and has been rescinded," Cecil added.
Ellender previously wrote a letter to Sen. Murray, D-Washington, saying "I'm hoping you can help me understand the intent of your request because it's hard not to conclude that DSCC politics have become so cynical that you actually expect people whom you routinely denounce to give DSCC money."
"If you could provide me some insight on what exactly you are asking of us and why, I would be most grateful," he added.
The Koch brothers and their company – the largest privately-owned company in the U.S. – are known for their involvement and contributions to conservative causes, including the tea party movement and conservative Heritage Foundation. Liberal groups and Democrats have launched ongoing campaigns against the brothers and their company.
However, according to opensecrets.org, the PAC associated with the company donated $30,000 to the DSCC during the 2010 election cycle and dolled out money to a few Democratic candidates, in addition to the many Republicans.
Senate Majority Leader Harry Reid, D-Nevada, used the brothers for an attack line in a fundraising email on behalf of the DSCC in March.
"If Republicans can knock just a few bricks free from our firewall, they'll force through their extreme agenda faster than you can say 'Koch brothers,'" the email read.