Timothy Garton Ash is a historian, political writer and Guardian columnist. His personal website is www.timothygartonash.com.

American politics have become so hopeless that I begin to be hopeful. From anger and disgust flow the energy for reform. In a CNN poll, 77% of Americans say elected officials in Washington have behaved like "spoiled children" in the crisis over the debt ceiling; 84% disapprove of the way Congress is doing its job.

A couple of years back, it was still vaguely original to describe America's political system as dysfunctional. Now the word is on every commentator's lips. More than that: it's official. In his address to the nation at the height of the crisis, urging patriotic compromise, Barack Obama said "the American people may have voted for divided government but they didn't vote for a dysfunctional government". Announcing the final deal, just 27 hours before default day, he talked of "the crisis that Washington imposed on the rest of America". But he's one of those elected officials in Washington too.

Why does the system work so badly? Decades of gerrymandering mean that politicians have to worry more about being deposed by members of their own party in primaries than convincing undecided voters in elections. This is what the Tea Party did to prominent Republicans before last year's midterms, putting the fear of Tea into moderate Republican members of Congress. It is now a verb – "he was primaried"…