Only in one extreme case....
WaPo "Right Turn" blogger Jennifer Rubin offers 15 reasons why Mitt Romney should pass on a third run for president. Her list is an excellent one.
That noted, there is one case where he could step up: if, for the first time since 1948, there is a ballot deadlock at the convention, with delegates unable to settle on a candidate. Romney could emerge as elder statesman. He'd have to address the liabilities JR lists--especially is inability to connect with ordinary voters. It would be a steep uphill battle. But if it proves the only alternative, he'd have to make a go.
Bottom Line. It almost certainly won't happen. But Mitt should not do what is known a Beltway parlance as "doing a 'Sherman'"--publicly state what William Tecumseh Sherman of Civil War generalship fame said of running for president: "if nominated I will not run; if elected I will not serve."
Letter from the Capitol, LFTC, Conservative Politics