(NEWS CENTER Maine) -- Senator Susan Collins reiterated her disapproval of special interest groups pouring money into political campaigns and issues Saturday following an advertisement by an advocacy group thanking the senator for her vote to confirm Justice Brett Kavanaugh to the Supreme Court.

According to the Portland Press Herald, A conservative group that poured more than $5 million into a campaign to defend Brett Kavanaugh launched a new ad buy this week: thanking Sen. Collins for her vote supporting the nominee.

Judicial Crisis Network is a 501(c)(4) advocacy organization – a so-called “dark money” group because it is not required to disclose the sources of its funding regardless of the industry groups or individual donors behind them. It poured at least $5.3 million into its pro-Kavanaugh advertising campaign, much of it targeting vulnerable Senate Democrats in red and swing states. At least $1.5 million of that was spent defending Kavanaugh after Christine Blasey Ford went public with her allegation of sexual assault against him.

The ad ends with a phone number for Collins’ Washington office. The group did not disclose the amount of its ad buy but said it would amount to more than $100,000 for television and digital ads.

WATCH THE AD BELOW

A liberal group of a similar stripe, Demand Justice, spent at least $700,000 of a planned $5 million campaign trying to scuttle Kavanaugh’s nomination.

Both groups represented the intense emotion and political energy generated by Kavanaugh’s nomination and confirmation fight, and both were subject to heated denunciations about how moneyed interests were clouding the debate.

Collins strongly voiced her disapproval of 'dark money' groups during her speech on the Senate floor regarding her decision to confirm Justice Kavanaugh.

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In a statement, Senator Collins' communications director Annie Clark wrote:

"Senator Collins is against dark money - period. It makes no difference whether it’s used by interest groups to praise her or criticize her. In Maine, we saw nearly double the amount of ads opposing Judge Kavanuagh’s nomination as we saw ads supporting him— that’s what she made reference to in her speech from the Senate floor."