The best way to think of these two pieces of legislation, then, is not to think of them as two entirely separate bills, but as a package deal representing $4.1 trillion in spending on the Biden agenda. And rather than restraining Democratic spending ambitions somehow, the infrastructure bill tees up the rest of the package, advancing the ball on the larger Biden agenda.

So when 19 Senate Republicans turn out to vote for the infrastructure deal, arguing that it’s a fully paid for compromise that doesn’t raise any taxes, they are effectively supporting a $4.1 trillion tandem package, and everything that may end up in it, even while pretending that they are adamantly opposed.

To understand why this happened anyway, it’s important to understand the almost mystical allure of bipartisan dealmaking in Congress, especially in the Senate. In parts of official and high-status Washington, bipartisan deals are seen as a good unto themselves, almost independent of what’s in them. And for a certain type of lawmaker, that allure has an even greater appeal now, in the post-Trump era, when one of the Senate’s own is in the White House. Biden himself is a true believer in the power of across-the-aisle dealmaking.