The U.S. Chamber of Commerce’s television ad buy against independent U.S. Senate candidate Angus King is double previous estimates.

The Chamber’s spent $400,000 for ad time in all Maine’s media markets for the 30-second spot "Mainers Know," according to independent expenditure filings with the Federal Elections Commission. The buy is twice the estimate calculated by the Press Herald, which was based on several public filings held by television stations in the Greater Portland area. 

Disclosure laws allow only for in-person inspection of political ad buys at television stations. The Press Herald was unable to inspect filings in the Bangor area where the USCC appears to have spent as much, if not more, on media time.

The ad is designed to bolster Republican senatorial candidate Charlie Summers, who this week earned the USCC’s endorsement. The ad dubs King the "king of spending" and "mismanagement," referencing his two terms as governor.

King’s camp has said the ad shows that USCC is out of touch with Maine values and his record helping business. Below is a photo that the campaign has posted on the campaign Facebook page.