The Koch brothers are the “financial engine of the Tea Party” despite denying they are "directly involved" in the movement, according to a Mitt Romney campaign memo.

Charles and David Koch, the billionaire brothers who own Koch Industries, have long championed libertarian and free-market policies. They have been heavily involved in bankrolling anti-regulation politicians and organizations.

The liberal blog ThinkProgress hailed the memo as a confirmation of their claim that the tea party movement was orchestrated by the Koch brothers -- not a spontaneous uprising of middle class voters.

The memo was obtained by The Washington Examiner. It suggested that the Republican presidential candidate hopes to court the tea party by by winning an endorsement from David Koch, who previously endorsed him in 2008.

Romney is scheduled to speak at the 5th annual Defending the American Dream Summit on November 4 and 5 in Washington, D.C. The summit is hosted by Americans for Prosperity, a group led by Koch.

Photo credit: Matthew Reichbach