The New Hampshire Democratic Party is launching a preemptive attack against former Massachusetts Republican Sen. Scott Brown in preparation for his possible Senate run in the state.

According to the New Hampshire Union Leader, the state party is beginning a campaign to highlight Brown's work for law firm Nixon Peabody, where he's engaged in business and government affairs work on various issues.

Though he's not registered as a lobbyist, the party organization is charging his work for the firm makes him a "shadow lobbyist" and is calling for him to disclose his clients. It's launching Web ads, an online petition and "organizing tools" to pressure Brown to release that information.

The former senator hasn't yet made his intentions clear, but he's floated the idea of running against Sen. Jeanne Shaheen Jeanne ShaheenOvernight Finance: US preps cases linking North Korea to Fed heist | GOP chair says Dodd-Frank a 2017 priority | Chamber pushes lawmakers on Trump's trade pick | Labor nominee faces Senate Lawmakers want Trump commitment to help Iraq post-ISIS Overnight Defense: FBI chief confirms Trump campaign, Russia probe | Senators push for Afghan visas | Problems persist at veterans' suicide hotline MORE (D-N.H.) next year and fueled speculation with frequent stops in the state to campaign and fundraise for New Hampshire Republicans.

The Democrats' online ads will run until Dec. 19, when Brown will headline a state GOP fundraiser in the state.

Brown previously faced questions from then-candidate Elizabeth Warren (D) about his client list during his work as a real estate lawyer during his 2012 Senate campaign.

Although he's not in the race yet, the New Hampshire GOP came to Brown's defense, characterizing the attacks as hypocritical because Shaheen's husband is the director of a law firm that also engages in lobbying activities.

“According to his own website, Senator Shaheen's husband is a 'government relations and lobbying attorney' — which would make him a “shadow lobbyist” according to the New Hampshire Democrat Party. Nobody can take the Democrats seriously given the glaring hypocrisy of their desperate attacks," said NHGOP Executive Director Matt Mowers.

--This piece was updated at 3:03 p.m. to reflect comment from the NHGOP.