The Republican strategy was unanimous opposition
"If we're able to stop Obama on this, it will be his Waterloo. It will break him." — Senator Jim DeMint, July 2009
Mitch McConnell, the Senate Republican leader, told his members it was "absolutely critical that everybody be together," so Democrats could never call the bill bipartisan.
The point: The bill was full of Republican ideas (the mandate and exchanges came from Mitt Romney's Massachusetts law). Republicans opposed it anyway, betting it would win them the 2010 election, as killing Clinton's plan had in 1994.
Jacobs and Skocpol, ch. 2, pp. 23–24