If Kerry does join the Obama administration, state law calls for Gov. Deval Patrick to appoint an interim senator to serve until a special election is held between 145 and 160 days of the seat being vacated.

Brown has not publicly said whether he would seek a return to the upper chamber, but close observers of Massachusetts politics have few doubts that the politically gifted, charismatic, and generally popular Republican would strongly consider a bid to duplicate his special election victory in 2010, when he claimed the seat long held by Ted Kennedy.

“From what I hear from people who’ve talked to Brown and are close to him, he definitely has interest in the special, if it happens,” said a Massachusetts Republican strategist. “But he hasn’t made up his mind that if it happens, he’s definitely going to run. He’s waiting to see where the appointment process goes, and then he’ll decide.”…

In a state with a short Republican bench, Brown likely would face significant pressure from within his party to jump back into the fray, considering his proven ability to win a hotly contested race in a non-presidential election year.