To the chagrin of many in his own party, President Barack Obama has almost always been willing to negotiate — on taxes, on spending, even on the social safety net.

But in the current fights over a potential government shutdown and the debt limit, the Democratic president has decided where he will draw the line.

On Thursday, Obama categorically rejected the Republican demand that he roll back the Affordable Care Act in order to keep the government open and also refused to entertain negotiations on raising the debt ceiling.