Sen. Bernie Sanders (V-I) is asking Tribune Co. not to sell its newspaper group to Koch Industries, the company of Charles and David Koch.

He's deeply concerned over the prospect of the billionaire brothers controlling blue-chip newspapers such as the Los Angeles Times, Chicago Tribune, Baltimore Sun, Hartford Courant, Sun-Sentinel and Hoy, the No. 2 Spanish language paper.

Noting in a letter co-written with Democracy for America's Jim Dean, Sanders noted the Koch family is worth an estimated $50B.

"Too much power resting in too few hands is not what America is supposed to be about," said Sanders. "We remain deeply concerned that one extremely wealthy family, because of an absurd Supreme Court decision, is able to have enormous influence over our political life and elections."

The Koch Brothers spent an estimated $400M during the 2012 election. 

Sanders, the most liberal member of the Senate, took a swipe at what he considers to be the conservative Koch agenda: "They have also established and funded dozens of organizations that actively support the privatization of Social Security, massive cuts in programs for working families, attacks on workers' rights, more tax breaks for billionaires and large corporations and other causes benefitting the rich and powerful.

"As the owners of a major fossil fuel company, they have also been leaders in providing substantial funding for organizations that spread misinformation about the reality of global warming -- a growing crisis which threatens our entire planet," he added.

The Sanders/Dean letter is addressed to Tribune CEO Peter Liquori, who is asked to reject any offer made by the Koch Brothers as he narrows down the list of potential acquirers of his newspapers.