However, single-party governance has proven politically unsustainable — and for a clear reason. Parties that achieve that control have used it for their own ends, rather than those of their constituents. The most recent four-year period of GOP total control ended in lobbyist-related scandals and conservative anger over bloated budgets.
The most recent two-year period of Democratic total control resulted in almost nothing except the passage of a bloated and pork-ridden stimulus bill, and the even-then-unpopular Obamacare system. The latter may have been a short-term victory, but it turned into such a long-term albatross that it may well prevent them from winning what should be an easy victory for Senate control in November. It’s certainly what cost them Senate control in 2014.
Political parties. You can’t live with them alone, and they can’t live with each other either. In other words, nothing boosts the desire for divided government than single-party control, and vice versa, as we see now.