Scott Brown on Saturday blasted Sen. Jeanne Shaheen Jeanne ShaheenPodesta floated Bill Gates, Bloomberg as possible Clinton VPs Obama signs 'bill of rights' for rape survivors into law Four military options for Obama in Syria MORE's (D-N.H.) challenge to limit outside spending in the New Hampshire Senate race as "self-serving and hypocritical."
Brown, the former Massachusetts senator who is gearing up for a run in New Hampshire, said Shaheen and other Democratic outside groups have already been running ads against him for months.
Brown made clear he thought the offer was a stunt.
"It's hard to view Jeanne Shaheen's actions as anything other than hypocritical and self-serving,” he said in a statement. “The people of New Hampshire can see through the Washington-style game she is playing.”
Shaheen on Saturday sent a letter to Brown asking him to sign the "People's Pledge," an identical document to the one he agreed to while running against Sen. Elizabeth Warren (D-Mass.) in 2012. According to a Sheheen's campaign, outside Republican-aligned groups have outspent Democrats in the state by three to one, totaling $1.5 million. Shaheen again urged Brown to sign "his pledge now" after his rejection.
"I have signed and attached two copies of an agreement with the exact same terms for the New Hampshire 2014 Senate race," Shaheen said in a letter to Brown. "I hope you will join me in once again committing to the same People’s Pledge you signed in Massachusetts and limiting the influence of outside groups in New Hampshire this year."
Brown announced Friday he is launching an exploratory committee to determine whether to enter the race.
"Before I even thought of becoming a candidate, Jeanne Shaheen's allies in Washington were running negative ads against me for months," Brown added. "And right now, while I'm meeting with the people of New Hampshire, she is on the West Coast raising money so third-party groups in DC will have money to run even more outside negative ads against me."
The pledge aims to take away the incentive for independent expenditure groups, individuals and super-PACs from spending in the race to either oppose or support a candidate.
If outside ads are run in the state, the pledge would require the candidate that benefits from the ad to pay 50 percent of the cost of the ad buy to charity. The pledge would relate to broadcast and online advertising and would cover negative and positive outside ads.
It does not, however, address outside spending on direct mail or field work in the state.
Brown is seen as one of the only Republicans who can make New Hampshire competitive in the 2014 midterms, due to his star power and heavy fundraising capabilities.
Brown signed the pledge in 2012 in one of the most expensive races in the country. After the pledge was signed with Warren, outside spending was only about one tenth of what the two campaigns spent, according to the Center for Responsive Politics. Outside spending totaled about $8 million compared to $77 million spent by Brown and Warren.
—Updated 12:50 p.m.