In laying out his proposal, aides said, Mr. Obama will expressly promise to veto any legislation that seeks to cut the deficit through spending cuts alone and does not include revenue increases in the form of tax increases on the wealthy.
Not so. What Obama actually promised was to veto any bill that changes Medicare benefits without raising new tax revenue. He has not promised to veto any Supercommittee bill that cuts the mandated $1.2--1.5 trillion in spending without raising taxes if it leave Medicare benefits untouched. So the debt ceiling deal could result in $2.5 trillion in spending cuts and no new revenue.
Because of the "triggers" in the debt ceiling deal, which mandate $1.5 trillion in spending cuts if the Supercommittee deadlocks or Congress does not pass its legislation, Obama cannot veto his way to tax increases yet. He can only keep crying out for revenue increases -- until the next round, when the Bush tax cut expiration looms. That's when he'll have to draw a real line in the sand.
UPDATE: here's the relevant bit from the speech transcript:
I will not support -- I will not support -- any plan that puts all the burden for closing our deficit on ordinary Americans. And I will veto any bill that changes benefits for those who rely on Medicare but does not raise serious revenues by asking the wealthiest Americans or biggest corporations to pay their fair share. We are not going to have a one-sided deal that hurts the folks who are most vulnerable."I will not support" does not equal "I will veto." And a deal that cut a further $1.5 trillion in spending arguably would not put "all the burden for closing our deficit on ordinary Americans" -- just 5/8 of it, if the goal is $ trillion in deficit reduction, and you add the Supercommittee's cuts to the initial $1 trillion. So Obama has some wiggle room to sign a Supercommittee bill that leaves Medicare untouched but is still all-cuts -- or perhaps more likely, one that adds some token amount of tax hikes to a trillion-plus in cuts.