Mere minutes after Scott Brown officially announced Friday that he was forming an exploratory committee for a U.S. Senate bid in New Hampshire, his erstwhile rival was rallying her supporters against him.

“It just happened: A few minutes ago, Scott Brown officially announced that he’s forming an exploratory committee to run against my friend Jeanne Shaheen for the Senate in New Hampshire,” Sen. Elizabeth Warren (D-MA) wrote in the email.

Warren bested Brown in Massachusetts’s 2012 Senate race, a contest the Democratic senator alluded to in the fundraising pitch.

Scott Brown may have moved to the Granite State, but we’re not going anywhere,” Warren wrote, urging supporters to help her raise $25,000 for Shaheen’s re-election campaign.

“In 2012, we ran a campaign based on our values. We said we were tired of a system rigged against working families, tired of values in Washington built on lobbyists’ money and influence, tired of one of “Wall Street’s favorite congressmen.” We said we wanted real accountability even for the biggest banks, and that we wanted to build a better future where the rules don’t always tilt for the big guys. We had that fight, and we won. Now we need to win again.”

Following his defeat to Warren, Brown joined Fox News as a contributor. His contract with the right-wing cable news channel was officially terminated on Friday after the exploratory committee was announced.

Brown will have his work cut out for him in his race against Shaheen, as history hasn’t exactly been kind to candidates who have tried to represent two different states in the Senate.