Jonathan Martin has the story:

Senator Marco Rubio has hired a coveted former aide to Mitt Romney to oversee his political activities in the Northeast and probably in a New Hampshire campaign, signaling that he is serious about a presidential bid.
Jim Merrill, who directed both of Mr. Romney’s New Hampshire primary bids, is joining Mr. Rubio’s political action committee as a senior adviser, a position that would put him at the helm of the Florida senator’s campaign in the first-in-the-nation primary state.
In landing Mr. Merrill, Mr. Rubio has not only brought on a strategist with deep experience organizing in New Hampshire, but also someone who was being pursued by other Republican presidential hopefuls. Mr. Merrill, who is based in Manchester, was sought out by a number of potential candidates, including Jeb Bush.