Portman may secretly think higher taxes are a price worth paying to reduce the deficit, but he's susceptible to the same pressures as all Republicans. After praising for the Gang of Six proposal, his office quickly clarified that Portman doesn't support tax reform as a means of increasing revenue. And all six of the Republicans on the committee have been given the seal of approval by anti-tax zealot Grover Norquist.
Brown's up for re-election this year in a state that just turned strongly red. So praising his Republican colleague is basically de rigueur. And now he's set a bar of reasonableness, so that if Portman joins other Republicans in insisting all deficit reduction come from cutting government services, and none from higher taxes on rich people, it's a "disappointment," rather than the predictable actions of a former George W. Bush budget director who promoted deficit exploding tax cuts.