Disclaimer. Don't rely on these old notes in lieu of reading the literature, but they can jog your memory. As a grad student long ago, my peers and I collaborated to write and exchange summaries of political science research. I posted them to a wiki-style website. "Wikisum" is now dead but archived here. I cannot vouch for these notes' accuracy, nor can I even say who wrote them. If you have more recent summaries to add to this collection, send them my way I guess. Sorry for the ads; they cover the costs of keeping this online.
Volden. 2002. A formal model of the politics of delegation in a separation of powers system. AJPS 46 (1):111-133.
Studies have come to mixed results when studying whether legislators delegate more under unified or divided government. Intuitively, one would expect more delegation under unifed government (because preferences are aligned). However, Volden reminds us that executives will fight to retain previously delegated power once the government moves from unifed to divided control, especially if th executive's preferences align with the bureaucracy's. Thus, it isn't only preferences that matter: it's (X1) preferences in relation to the status quo and (X2) the possibility of an executive veto. Though Epstein and O'Halloran assert that including an executive veto would not change their comparative statics, Volden presents a model showing the reverse.
Research on similar subjects