There's a step in the American electoral process that comes before the primary. Maybe you've taken part in it, maybe you haven't, maybe you don't even know about it, but you can't just walk up and say 'I want to be on the ballot'. Before you can do so, you have to gather signatures from people who would support your bid for election or re-election. The number of signatures required is ridiculously low- a couple thousand people is all- and so while it's technically a barrier to entry, it's not really much of one if you're at all organized in the absolute slightest. Even candidates deep in enemy territory, even candidates who have ticked off their constituents and are about to be thrown out of office with torches and pitchforks, can at least turn up enough people to get them on the ballot so they can be slaughtered on schedule. The only way it ever knocks people out of the race are if they make a beyond-gigantic screwup, get more or less defrauded out of the race when opposition supporters tally the signatures, or if they're so minor and so unknown and so utterly unorganized that their "campaign" is incapable of even this most simple of tasks.
Thaddeus McCotter, a House Republican from Michigan since 2003 and therefore a person who has undertaken this task a minimum of five times prior, has somehow managed to prove incapable of this most simple of tasks. He could hand in 2,000 signatures- which he did- and at least 1,000 had to be ruled valid- which were not. As a result, McCotter now has to attempt to win his seat back via the write-in ballot, throwing the door open out of nowhere to a Tea Partier named Kerry Bentivolio- who now can sleepwalk to the Republican nomination- and two Democrats, William Roberts and Syed Taj, that did manage to get the signatures, as well as more prominent names who may now opt to take on McCotter via the write-in route as well.
The heck of it is, had McCotter just completed this one simple task, the rest of the campaign would have been easy sailing for him.
Now, this isn't entirely unprecedented for someone prominent to fail to get the signatures. In fact, we don't have to leave this election season. In the Republican Presidential primary, potential nominees made it look somehow difficult. Five different candidates failed to get the signatures required to make the ballot in Virginia, which has also seen a Senate hopeful, David McCormick, miss out. Three candidates made at least partial failures in Illinois. Rick Santorum failed to get on in DC and Indiana and made a partial miss in Ohio. Jon Huntsman Jr. failed in Arizona. Newt Gingrich failed in Missouri.
And then there's the third-party effort made by Americans Elect, which somehow managed to get on the ballot (in 29 states) and then failed to get a candidate to put on that ballot.
Usually it's not anywhere near this hard. But maybe it's best they fall off the ballot here. If they couldn't even get this right, how can you expect them to handle something as complicated as holding public office?