If the president's chances of convincing Congress to authorize strikes against Syria hinge on public support, he's in a lot of trouble. Today, a new Pew Research survey shows that the public's opposition to strikes has increased significantly over just the past week, rising from 48 to 63 percent opposed.

But it's the total collapse in Republican support that's really striking (no pun intended). Back in April, when Pew asked voters whether they would support strikes if Syria used chemical weapons, Republicans were pretty supportive; 56 percent were on board, compared to just 24 percent opposed. By last week's Pew Research survey—now simply asking voters whether they would support strikes now that Syria had used chemical weapons—Republicans were basically divided. But today, Republicans are overwhelmingly opposed by a 49 point margin, with just 21 percent in support and 70 percent opposed. There hasn't been similar movement among Democrats.

Pretty staggering. Now here's the great question: Are Republicans getting more opposed because they're reflexively opposed to President Obama, or are Democrats staying supportive because they're giving the president the benefit of the doubt?