On the eve of yet another round of high-level meetings at the White House aimed at forging a “grand bargain” to cut the deficit by $4 trillion over 10 years and tackle the debt ceiling impasse, Speaker John Boehner released a statement saying that he is pulling out of those talks. What caused the break: “The White House will not pursue a bigger debt reduction agreement without tax hikes.” Support for tax increases — or even closing tax loopholes, as Democrats have suggested — is increasingly seen as a litmus test for Republican lawmakers in the lead-up to action on the debt ceiling. Already sensing the tides moving, several of the Republican presidential candidates have come out against voting for any deal that involves tax hikes or, in the case of Michele Bachmann, any deal period. That said, Washington observers had expected Boehner to seriously consider (behind closed doors, of course) the notion that boosting revenue might be necessary to plug the deficit hole and right the nation’s finances. But perhaps Republican leaders are under more pressure from their base than we realize. (Or perhaps they’re just feeling ballsy.) As for the Speaker, he is now in favor of a smaller $2 trillion deficit-reduction and debt deal being hashed out by Vice President Joe Biden and a bipartisan group of legislators.