Meet the GOP's answer to Democrats' Koch brothers attacks : the Steyer brothers.

A new web ad from the the conservative group American Commitment seeks to cast the Steyer brothers as the liberal equivalent of the Koch brothers, whom Senate Majority Leader Harry Reid (D-Nev.) has repeatedly attacked for trying to "buy America."

The ad features footage of Reid attacking the Koch brothers but suggests his criticisms more aptly describe the Steyers -- Tom and Jim -- whom it accuses of opposing the Keystone XL pipeline for personal gain.

"That’s why Tom Steyer and his brother Jim are spending millions to finance campaigns that support liberals who will keep Harry Reid in charge of the Senate," the ad says.

The ad buy is relatively small -- $50,000 -- and will be online only, but it previews the GOP's defense against Koch brothers attacks going forward (to the extent that Americans actually care about such things).

It will run in Washington D.C. and also the states where the Democratic group Senate Majority PAC is running Koch brothers attack ads: Louisiana, North Carolina, Arkansas and Michigan.

Tom Steyer has suggested he might spend as much as $100 million on the 2014 election, and the Koch brothers are already well on their way to spending that much.

Asked about the Koch brothers comparison recently, Jim Steyer embraced it.

"I take that as a compliment,” he told Politico recently.