Liberals have been pointing out how frustratingly lacking in rationale the Nelson/Collins group seems to be. I fully agree. They took a $900 billion stimulus and decided to knock off a nice round hundred billion dollars because that shows they're centrist. If the House had passed a $1 trillion bill, they would have decided $900 billion was the perfect figure. This is essentially the same way they operated with the Bush tax cuts.
Of course, when Senate centrists did knock down the cost of the Bush tax cuts a bit, and thus declared that centrism has prevailed, Republicans just turned around in conference committee and made the spending cuts meaningless. For technical reasons, I don't think Democrats can do the same thing this time. But I do think they can reverse the state budget aid cuts, which is the most damaging cut the centrists imposed, and swap it for something else. In fact I think a conference committee could undo a lot of the damage, and probably bring the price tag up a bit.
The question is, will the centrists really hold out and kill the bill at that point? They certainly weren't willing to do that to the Bush tax cuts in 2001 after the Republicans neutered their input. I don't think they would this time, either. The point was to establish that they're centrists -- important dealmakers who can take whatever bill emerges and make it somewhat less so. The point has been made clearly. I don't think they particularly care about the specifics. If their changes are reversed in committee, and they can quietly vote for the final product, they probably will.