The policy merits of the budget deal struck between President Obama and the Tea Party – no other group seems to have exerted serious influence – aren’t terribly interesting. If you subscribe to the mainstream tenets of macroeconomic thought, it will have a small, negative effect on unemployment, partially offsetting the benefits of the tax cut deal agreed to last December. If you instead subscribe to the small but politically influential subset of right-wing dissidents who believe that the government should respond to a liquidity trap by decreasing its deficit, then you think it will exert a small positive influence.

What’s more interesting is the politics. I’m not sure I can think of an example of a party that leverage control of one House of Congress into significant policy movement in its direction on a high profile issue. When Democrats took control of the Senate in 2001, there was the sense that they could limit the ambition of President Bush’s domestic agenda, but nobody considered the possibility that they could force Bush to move policy in their direction as a condition for keeping the government open. Even when the Democrats won both Houses of Congress in 2006, they used their leverage merely to veto additional policy changes in Bush’s direction, not to adopt their own policy goals opposed by Bush.

So why didn’t President Obama at least fight the Republicans to a draw? Why, if he had to move in their direction, did he wind up adopting deeper cuts than even John Boehner originally proposed?

A few factors leap out. First, the Democratic coalition is dominated by people who favor a conciliatory political style. Substantive beliefs about policy aside, most Democratic voters want their elected officials to take what seem to be reasoned, compromising positions. The Republican coalition, by contrast, is dominated by voters who want their leaders to take strong, uncompromising stances.

Second, arguing about government spending in the abstract favors Republicans. People do not believe in (or, I would put it, understand) Keynesian economics. So arguing that spending cuts inherently jeopardize the recovery is a losing proposition. When the category is domestic discretionary spending, a catch-all category, it’s difficult to turn the debate into one of specifics, since so many actual programs are affected.