To understand why, turn back the clocks to December 2010, when Democrats still controlled the House and Senate Republicans were busy caving to Obama on everything from the New START nuclear agreement with Russia to ending the military's "Don't Ask, Don't Tell" policy.
Some on the left, including Brian Beutler who was then with Talking Points Memo, worried that the new Republican majority in the House would demand concessions on spending when the debt limit was reached some time in 2011. So, Beutler asked Reid why he did not push to include a debt limit hike in the tax legislation that Obama signed that month.
Reid responded, "I want the Republicans to have some buy-in on the debt. They're going to have a majority in the House. I think they should have some kind of a buy-in on the debt. I don't think it should be when we have a heavily Democratic Senate, a heavily Democratic House and a Democratic president."
So, Reid knew the debt limit would expire. He knew House Republicans would demand spending cuts in return for raising the debt limit. But he decided not to raise the debt limit anyway.
Reid wanted a fight. He wanted, in Beutler's words, to "watch [John Boehner] squirm."
I hope Reid has enjoyed the show.