Charles and David Koch, the billionaire brothers who run Wichita, Kansas-based Koch Industries Inc., added $1.3 billion to their collective fortune yesterday on reports that U.S. industrial production gained more than forecast. The surge elevated their net worth to more than $100 billion, according to the Bloomberg Billionaires Index.

The Koch’s ascent comes as Freedom Partners, one of their fundraising networks, last week aired its first batch of television ads targeted at this year’s U.S. Senate races, including commercials knocking Democratic Senator Mark Udall of Colorado and Representative Bruce Braley of Iowa for supporting President Barack Obama’s health-care law.

“The Koch brothers are pouring millions into this,” Chris Harris, a campaign spokesman for Senator Udall, said in an e- mail yesterday. “They’re only fighting for their own interests, not Coloradans’. Mark Udall has a long record of fighting for the middle class and stops at nothing to protect Colorado’s special way of life.”

The ads represent an escalation in TV warfare among outside groups intervening in the Iowa and Colorado contests. In both cases, Americans for Prosperity, another Koch organization, criticized Democratic candidates for backing the health-care law.

‘Pocketing Money’

“These professional politicians claim to be standing up against health insurance companies while pocketing money from their political action committees and company executives,” James Davis, a spokesman for Arlington, Virgina-based Freedom Partners, said in an e-mail last week. “It’s hypocritical -- while health insurance companies stand to see massive financial gains from the health-care law, the rest of America is left paying the bill.”

Jeff Giertz, a spokesman for Braley’s campaign, said the Kochs and the GOP candidates they support stand behind policies that would hurt Iowa’s economy.

“Bruce Braley fights for Iowa’s working families because that’s where he comes from, and he’ll keep fighting for Iowa in the U.S. Senate,” Giertz said in an e-mail yesterday.

The Koch’s fortune is derived from their combined 84 percent stake in the second-largest closely held company in the U.S., which has annual sales of about $115 billion, according to Koch Industries’ website. They’re the fifth- and sixth-richest people in the world.

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