We investigate the motivations driving members of the US Congress to introduce bills that require new federal spending, testing a classic “party matters” hypothesis that spending is motivated by partisanship with Democrats spending more on social programs and Republicans more on defense and social order. To test this hypothesis, we introduce a new dataset that codes Congressional Budget Office reports, allowing us to link cost estimates to over 7,000 congressional bills. Overall, we find very little evidence that partisanship or ideology can reliably predict the cost of bills. Bills introduced by Democrats call for similar levels of new spending as those introduced by Republicans, even on policy topics where partisan divisions are thought to be pronounced. These results raise the possibility that when it comes to spending rank-and-file members are less motivated by abstract partisan commitments than traditionally thought.