It looks obvious

William Niskanen, a former economic adviser to Ronald Reagan, speculates that divided government itself may be the key to fiscal restraint. Using data going back to Harry Truman’s time, he found that real annual growth per head in federal spending averaged 1% under divided government and five times that under unified government.

With no hostile Congress to block him, Mr Bush has been free to follow his political instincts. There was once some ambiguity about what these were. When he first ran for president, he said he believed in limited government, and boasted that if his race with Al Gore were a spending contest, “I would come in second.” But he also distanced himself from Republicans in Congress by accusing them of “balanc[ing] their budget on the backs of the poor.”