PORTSMOUTH, N.H.—Democratic Sen. Jeanne Shaheen on Saturday blamed GOP rival Scott Brown for the nasty wall-to-wall ads hitting New Hampshire voters in the runup to Tuesday’s election, pointing to his failure to sign a pledge earlier in the cycle to keep outside money from pouring into the state.

That criticism may have a special resonance in the final days of the election for voters eager for the back-to-back TV and radio spots to end.

“When my opponent first got into the race, I challenged him to take his own People’s Pledge that he came up with in Massachusetts when he was running against Elizabeth Warren,” she said in an interview following a “Get Out the Vote” event in Portsmouth, New Hampshire. “What we saw in that race is that that shut down those third party groups, that third party money that came in, almost totally. It reduced the number of negative ads by about 50 percent in Massachusetts."

On the ground here, it’s impossible to turn on the TV or radio without seeing or hearing attack ads lobbed against either Shaheen and Brown. Those ads are in large part funded by outside groups, with national Democratic groups seemingly just as active on air as Republicans.

"He said that was going to be good for the voters of Massachusetts, but he wasn’t willing to say that would be good for the voters of New Hampshire," she said. “It’s really disappointing he wasn’t willing to agree. ... I challenged him. I had signed it.”

Shaheen has frequently attempted to undermine Brown’s New Hampshire bona fides by linking him to outside parties, including the billionaire Koch brothers. She has also faulted him for pushing national issues in a race she says should be about New Hampshire concerns.

She firmly dismissed questions on whether she wasn’t also actively tapping into and relying on national Democratic allies to turn out the vote. “No. Again, there are two people on the ballot on Tuesday. This race is about who is going to be good for New Hampshire,” she said.

On Friday, the Shaheen campaign went up with a radio spot featuring an endorsement from President Bill Clinton. On Sunday, former Secretary of State Hillary Clinton will visit New Hampshire to stump for the incumbent Democrat.