This paper tests the widely held assumption that left-wing cabinets favor higher public spending and examines whether cabinet ideology affects the persistence of major fiscal adjustments. In a panel of large fiscal adjustments in OECD countries during the last 40 years, we find evidence that left-wing and right-wing cabinets are partisan: the left tends to reduce the deficit by raising tax revenues while the right relies mostly on spending cuts. Our testable hypothesis is that cabinets can signal commitment by undertaking fiscal adjustments in ways that are not favored by their constituencies. In other words, the left gains credibility when it cuts spending while the right becomes more credible when it increases tax revenues. Probit estimates of the determinants of persistence in fiscal adjustments confirm that spending cuts by the left and tax increases by the right are associated with persistent adjustments. The effect is significant for cuts in public spending, public consumption (wage or nonwage), increases in total revenues, direct taxes on businesses and other taxes. We test for the role of several other determinants of persistence, confirming that coalition and majority cabinets are associated with less persistence while periods of high or rising levels of indebtedness favor persistence. The estimates of the impact of ideology and other variables on GDP and its components show that it is the size of the spending cut rather than cabinet ideology that is most important.