The New Hampshire Democratic Party is requesting a Federal Elections Commission investigation into whether Republican Senate candidate Scott Brown failed to report campaign expenditures while he was exploring a bid.

In the nine-page complaint, the party also questions whether Brown may have filed as a candidate later than required by FEC regulations, following his admission this weekend that he decided to make his bid on Feb. 14, though he spent the subsequent month saying he hadn’t yet made a decision.

"Scott Brown decided to become a candidate for Senate on Valentine’s Day, and that should have triggered FEC filing requirements and deadlines that he clearly did not meet. We're asking the FEC for a thorough and swift investigation,” said New Hampshire Democratic Party Chairman Ray Buckley in a statement announcing the complaint.

“For five weeks after he decided to become a candidate, Scott Brown refused to admit it, misleading the people of New Hampshire, ducking the law, and using his spot on Fox News to attack Jeanne ShaheenCynthia (Jeanne) Jeanne ShaheenSupreme Court to hear online sales tax case State official indicates US military role in Syria post-ISIS centered on Iran Overnight Health Care: Dems press HHS pick on drug prices | Alexander, Trump discuss ObamaCare fix | Senate Dems seek B to fight opioids | Maryland eyes ObamaCare mandate replacement MORE."

Federal election laws define a candidate as anyone seeking office who has received contributions or made expenditures in excess of $5,000.

Within 15 days of hitting that threshold, an individual must designate a campaign committee, and within 10 days of designating a campaign committee an individual must file a statement of organization.

Brown didn’t file his statement of candidacy with the FEC until March 20, more than a month after he says he decided to jump in the race.

During that month, however, its unclear how much — if anything — Brown spent toward his planned bid before he officially launched it.

Brown’s campaign says he had no overhead during that time — no staff, no exploratory polling, no office — and so the only expenditures he made were after he officially announced his candidacy.

Brown and his team did engage in a flurry of activity in the weeks after he announced his candidacy on March 14, but didn’t report any expenditures during that period in his first finance report to the FEC, an omission which the NHDP alleges in its complaint “appears to have violated federal law.”

An aide for Brown’s campaign dismissed those charges, however, saying that Brown hadn’t received bills for any of those expenditures and that all of them would appear on his next filing.

“Scott Brown formed his exploratory committee on March 14. In those early days, the biggest expense we incurred was gas for Scott's pick-up truck. We just moved into our campaign headquarters, and as bills get submitted, they get paid," said Lizzy Guyton, Brown's communications director.

The NHDP’s complaint comes just days after the New Hampshire Republican Party also filed a complaint with the FEC against Sen. Jeanne Shaheen’s (D) campaign, alleging she attempted to illegally coordinate with a Democratic group with ties to Senate Majority Leader Harry ReidHarry Mason ReidDems search for winning playbook Dems face hard choice for State of the Union response The Memo: Immigration battle tests activists’ muscle MORE (D-Nev.) that’s aired ads supporting her reelection bid.

And it indicates that Democrats are taking the NHGOP’s allegations seriously enough to respond with some of their own.

Neither investigation, if they proceed, is likely to conclude before Election Day, but they provide a foundation for potentially weeks of attacks.

Democrats have already been accusing Brown of lying to the public, and critics have questioned whether he profited by misleading Fox News, which suspends contracts when commentators have made an intention to run for office clear. Fox didn’t officially cancel its contract with Brown until he announced his plans publicly.

On Wednesday, former New Hampshire Gov. John H. Sununu (R) called on Shaheen and Senate Minority Leader Harry Reid (D-Nev.) to pull the ad in question in the NHGOP’s FEC complaint, declaring that “it appears the public trust has been violated.”

The dueling FEC complaints are the latest indication the New Hampshire race may ultimately be one of the nastiest in the nation.