It's essentially a repeat of the 2011 debt ceiling fight, an attempt to use the financial stability of the country as a bargaining chip for a minority block of one chamber of Congress to dictate terms to the rest of the country. Last time it was the Republican minority in the Senate using the filibuster to prevent anything from passing, this time it's the Tea Party throttling the House Speaker into making sure that bill comes up for vote in the House that would pass without their say-so.
The Senate fight last time was kind of inconclusive. The President tried to actually negotiate, and ultimately they came up with the 'sequester' to square the circle, which as everyone expected went from being an unthinkable consequence to now being the rational middleground between both Party's demands. The Democrats scared the Republicans into abandoning their tactic, and the Republicans got their idea of a budget (i.e. massive spending cuts everywhere) to be the new 'normal'.
Now the Tea Party, bitter upon slowly finding out in the last election that there is no vast silent majority urging them on but still sure it exists to be won, are trying to threaten the same thing. They essentially want to invalidate that Obama was ever actually President, and since the mainline Republicans essentially negotiated a resolution without them but got what they wanted, they think if they actually go over the cliff this time they'll get the Democrats to agree to absolutely anything, and somehow escape all blame for the consequences.
We're basically left to hope that John Boehner, who may be soulless but by no means brainless, will eventually realize that this tactic is actually going to be a problem. This cannot be allowed to become the way things operate. It's not about the Republicans being jerks, because someday the shoe is likely to be on the other foot. It's about stopping this tactic before anyone decide it's a good idea.