In many federal countries, local governments run large deficits, even when fiscal supervision by state authorities is tight. I investigate the extent to which party alignment of governments and fiscal supervisors influences budget deficits. The data set includes 427 German local governments for the period 2000–2004. I exploit a period after a far‐reaching institutional reform that entirely re‐distributed political powers on both the government level and the fiscal supervisor level. The results do not show that party alignments of governments and supervisors (co‐partisanship) drive short‐term deficits. Instead, I find that the ideology of partisan governments and supervisors matters: left‐wing local governments run higher deficits than their right‐wing counterparts; left‐wing supervisors tolerate higher deficits than right‐wing supervisors. These findings imply that political independence for fiscal supervisors is recommended.