Former Massachusetts Republican senator Scott Brown officially launched his bid for U.S. Senate in New Hampshire Thursday, hitting Sen. Jeanne Shaheen (D-N.H.) over her support of the federal health-care law.

Brown made his announcement in a speech in Portsmouth and also tweeted some remarks, including a play on the New Hampshire state motto -- "Live Free or Die" meant as a jab at the health-care law.

Democrats launched a preemptive attacks against Brown earlier Thursday.

"We’ll see Scott Brown in Portsmouth tonight, saying exactly what he’s been saying forever. And demonstrating more clearly than ever that he’s not running to serve New Hampshire. He’s running to advance his own interests and the Big Oil, Wall Street guys who pay for his campaigns," said former state Democratic Party chairwoman Kathy Sullivan.

A new WMUR Granite State Poll released Thursday showed Shaheen leading Brown 45 percent to 39 percent. In January as Brown was still mulling a bid, Shaheen led by 10 points.

Brown was first elected to the Senate in a 2010 special election upset. He lost to now-Sen. Elizabeth Warren (D-Mass.) in 2012. He sold his Bay State home last year and moved to his former vacation home in New Hampshire.