NextGen Climate, a super PAC backed by billionaire Tom Steyer focused on climate change, is unleashing a substantial TV, radio and online advertising blitz against Brown, according to Pete Kavanaugh, state director for the group.

Two federal super PACs are launching a barrage of ads against Republican Scott Brown in his New Hampshire US Senate bid.

Also on the attack: Mayday PAC, a super PAC aimed at ending super PACs and reducing the influence of money in politics. It’s set to start airing a strange TV ad on Friday boosting one of Brown’s longshot GOP opponents, former state senator Jim Rubens, ahead of the Sept. 9 New Hampshire primary.


NextGen’s 30-second TV ad emphasizes Brown, the former Massachusetts senator, is an “out-of-state” politician who is backed by the “out of state oilmen like the Koch brothers.” Echoing a common Democratic attack, the spot also criticizes a 2012 vote by Brown against allowing a bill aimed at curtailing certain tax benefits for large oil companies from moving forward.

The campaign, which includes a similar 60-second radio spot and a shorter version of the TV ad for online, is backed by a buy in the “high six-figures” over the next three weeks, Kavanaugh said.

The Mayday PAC spot stars a man, “Honest Gil” who says he is a “career politician.”

“This is an unprovoked attack on Jim Rubens,” the man says. “You see, me and my buddy, Scott Brown, we want to take your tax dollars and hand them out to the cronies and lobbyists who bankroll our political campaigns.”

In a faux-negative knock at Rubens, the man says Rubens wants to “stop corruption.”

The PAC, launched by Harvard Law School professor, author, and activist Lawrence Lessig, is supporting both Democratic and Republican candidates this cycle. The group is “working to fundamental change the way elections are funded” said a spokeswoman, Allison Bryan.


She said while the group doesn’t support any specific policy prescriptions, it does support small-dollar campaign financing and is working “to elect a Congress committed to reform.”

Bryan said the ad is airing on New Hampshire broadcast and cable television and is part of the PAC’s $600,000 TV and radio effort boosting Rubens through Sept. 9.

The Brown campaign had no comment on the new attacks.

Also running in the New Hampshire GOP primary is former US senator Bob Smith. The winner will take on Democrat Jeanne Shaheen, who is running for her second term in the US Senate.

Joshua Miller can be reached at joshua.miller@globe.com. Follow him on Twitter @jm_bos.