Colorado Springs — Billionaire Charles Koch on Sunday thanked former Senate Majority Leader Harry Reid, D-Nev., for criticizing him relentlessly on the Senate floor, which he said helped him sell more books.

"Thank you, Harry," Koch told prospective donors at his Seminar Network conference on Sunday.

"I owe him big. Boy he made my book sell a lot better," he said to laughs.

Reid attacked Koch and his brother David relentlessly from the Senate floor during his last few years in office, in an effort to help turn national elections toward Democrats.

In 2014, Reid called Koch a "sulking billionaire" who tried to "buy" the Senate for Republicans.

That same year, Reid claimed the Kochs were a major factor in climate change. "Charles and David Koch are waging a war against anything that protects the environment," Reid said.

In 2016, his last year in office, Reid accused the Kochs of funneling "dark money" into the political system.

The Seminar Network is a gathering of donors to the various groups the Kochs fund. Koch and other speakers have said throughout the weekend that the goal of the group is to reach out to disadvantaged people and help them succeed. The groups have also stressed support for tax and healthcare reform, two issues that the Republican Congress is still struggling to pass.