Politico:

Former Massachusetts GOP Gov. Mitt Romney will not seek the Senate seat vacated by Ted Kennedy’s death, a Romney spokesman said Thursday.
Responding to speculation that Romney may be interested in the seat — which he challenged Kennedy for in 1994 — Eric Fehrnstrom, a spokesman for Romney’s political action committee, told POLITICO that the former one-term governor has no interest in campaigning to replace Kennedy.
“Gov. Romney’s focus right now is on helping other Republicans run for office, and that is how he will be spending his time,” he said.