The Federal Aviation Administration is the United States agency responsible for air traffic control, aviation permits and licensing, regulatory enforcement and other air safety roles. It's kind of like Transport Canada and Nav Canada rolled into one. They are a government body, a subsidiary of the US Department of Transportation, so natually they are federally funded. The federal bill (bill as in proposed legislation, not as in a really, really large denomination banknote) that provided funding to the FAA expired almost four years ago, so ever since the agency has been financed through a series of twenty temporary extensions to that bill, as the parties involved haven't been able to reach a new long term agreement.
I would tell you what the contentious point was in the negotiations, but after so many iterations, it may be that the issues on the bill that won't pass are not the original issues. To prevent a bill from passing, or to force passage of legislation that opponents would otherwise vote down, American politicians can attach tangentially related riders to each others bills, and also name them, so that a bill proposing that no one under twenty-one be permitted to have a e-mail account could be called the "Anyone who opposes this bill is a pedophile bill of 2011" or a bill forbidding convicted pedophiles from working in ice-cream trucks could have a rider attached to it that forbade teaching kids under twelve what a condom was. So the people are discouraged from voting down either hypothetical bill lest they be branded pedophilephiles. My information on U.S. politics is largely derived from late night comedy shows, so check the comments for knowledgeable Americans explaining how this system makes sense.
Anyway, the new FAA funding bill seems to be held up by a point of labour relations, that would return airline and railroad workers to an older system of voting to form unions. The old system allowed unionization in a airline workplace only if a majority of eligible voters vote yes. That is, anyone who doesn't bother to vote is counted as a no. That sets apathy to the employers' advantage and seems to me to be open to abuse through intimidation, because employers can identify the unionizers through who attends the polls, so it jeopardizes the idea of secret ballot. The new system, only recently ruled valid, allows employees of airlines and railroads to form a union by a simple majority of only those voting. That goes too far in the other direction, in my opinion, because it allows a small group of committed unionizers to take advantage of widespread apathy and establish a union that wasn't generally wanted. I would propose a compromise that requires both a majority of votes cast, and a majority of the eligible voters to turn out. After all, if the majority of the workers can't be arsed to go to the polls to change their working conditions, I'm thinking those working conditions can't be so bad. It's still open to intimidation or employer tricks--e.g. manipulating shifts--to keep people from voting, but it avoids assigning opinions to people who didn't express them. The Democrats (the leftmost of the two main American parties) don't want to go back to the old way, so they want the labour issue removed from the bill, thus are preventing that bill from passing.
In retaliation, or some differently-worded political version thereof, the Republicans (the rightmost most of the two parties) have worded the twenty-first iteration of the extension to the old FAA funding bill to include a provision eliminating federal subsidies for airline service to thirteen rural airports, including of course airports in the constituencies of some prominent Democrats. I note that requiring market-based prices for service from rural airports would not cut people off from food or medical attention without air service. These are places like Ely, Nevada (four hours drive from Las Vegas or Salt Lake City), Glendive, Montana (three and a half hours out of Billings) and Morgantown, West Virginia (an hour and a half drive from Pittsburgh), all on paved, year-round highways. Each of those towns has its own hospital and real grocery stores. Morgantown seems pretty odd to be on that list. I think there are people in Toronto who have to drive more than an hour and a half to get to an airport with scheduled service. And the non-subsidized fares are dirt cheap. I found a round trip from Billings to San Francisco for $118! There must be some historical reason for the subsidies.
All of the above is ignorable background to what I think is the most interesting point, that if the dispute isn't resolved, the FAA's operating authority would expire. Air traffic controllers are deemed an essential service and would continue to work, but 32,000 other FAA employees: presumably inspectors, examiners, file clerks, janitors, approach designers, dangerous goods safety coordinators and all manner of other people I'm not thinking of would be out of work. I found it especially interesting that with the FAA losing its mandate in that way, they would also lose the ability to levy and collect fees. People I know in the appropriate level of US airlines are actually looking at ways to refund or stop charging FAA fees if this happens.
I'm pretty sure the delay is just a game of political chicken, and that the deadlock may be broken by the time this even posts, but it's kind of freaky to think that this is the way a country would go from a world power to a failed state. One by one government agencies would lose their ability to function. While a lot of what any given agency does might be unneeded bureaucracy, once the normal way to get a pilot licence has gone away, you'd presumably get one by paying a guy who kept the machine that prints them after his last paycheque bounced. Or maybe they'd consolidate and transfer the authority to another overworked agency, until the police or the military run everything.
Please forgive me, south-of-the-border (and north of the other one) readers for mangling your political system. Blame the news media, summer heat, and the desire to post this before it became entirely irrelevant, as opposed to after doing sufficient research.