Most Congressional votes follow strict party lines these days. But the resolution authorizing the president to strike at Syria for using nerve gas against its own people scrambles those polarizing propensities. Both parties are divided, and the president can only prevail by fashioning the sort of bipartisan coalition he has tried -- and largely failed -- to build around other issues.Since the early '70s, the GOP has portrayed itself as more willing and able than the Democrats to employ American power.