The voter fraud has already started

The much reviled Nancy "Impeachment is off the table" Pelosi is up for relection this year, and is being challenged by activist Cindy Sheehan. (You may remember Cindy. Her son was one of the first soldiers to die in Iraq, and she spent a summer camped out in front of the White House at a time when no one else was willing to protest the war.)

As an Independent, in order for Cindy to get on the ballot, she needs a lot of signatures of registered voters in San Francisco by this Friday. California has some very strict ballot laws, and if successful, Cindy would be only the 6th Independent candidate ever to get on the rolls.

Last Friday, a week early, she turned in over 40% more signatures than she needed to the Election Board. Everything looked great, and it seemed she was going to really give Nancy Pelosi a run for her (party's) money.

The election board did a "random sampling" of 531 of the signatures, and determined that 300 were registered voters and are "challenging" the other 231. This allows them to determine that 43.5% of her signers aren't registered voters, and thus she can't be on the ballot (unless she gets 2,000 more good signatures by this Friday). The process is lengthy, and the election board had done a random sampling previously of the signatures she'd turned in before this point - that batch had only a 22% "challenged" status. Now she hands in 10,000 more signatures, and the percentage doubles?

That seems suspicious to me. Pretty much no matter how you slice it, this means something unethical has happened. Here's some possible interpretations:

1. The people of San Francisco could be so nutso that 43.5% of them listened to the people with the clipboards speak long enough to get to sign, and then wrote fake names.
   (I don't know about you, but if someone tries to get me to sign something on a street corner, I either ignore them and walk away, or agree with them and listen and sign. It's never occurred to me to sign a fake name to undermine them. Even if it had, it seems a dubious tactic and a waste of my time. Could 43.5% really do that? Are "we, the people" that dumb?)
   
2. Someone on Sheehan's campaign could have been corrupt, and signed thousands of false names to get her on the ballot. Considering that Sheehan is running as the reform candidate, this seems unlikely, but it's not impossible. People do do dumb things - but you'd think even 10 or 20% of the signatures being in the same handwriting would stand out.
3. Someone on Sheehan's campaign could be a stooge or tool of either major party, and signed thousands of false names in an attempt to trick Sheehan into not getting enough signatures. Again, thousands of made up names in the same handwriting seems awfully risky, but as I said, people do stupid things.
   
4. The voter registration lists could have been purged by the election board (much as they were in Florida in 2000) such that 43.5% of San Francisco voters will learn in November that they aren't registered to vote after all.
5. Someone at the election board could have gone fishing for unregistered signatures, then combined that list with a random sampling so as to create a "challenge-able" percentage that was just a few points higher than what she'd exceeded the requirements by.

Personally, I think scenarios #4, and #5 are the most believable. They're certainly easier to carry out than scenarios 1-3, with less risk of exposure. If the answer is just scenario 1 stupidity, I'm going to be very disgusted with my fellow Americans.

Obviously, there's motive for someone to subvert the election system - the entrenched pro-establishment anti-Impeachment Pelosi has power back home and is in danger of being ousted, so it's possible a Democrat at the election board might do this to protect her. Considering the history of the Bush Administration rigging elections, it's possible a Republican might do this, too - and they'd likely anticipate that if Pelosi remains in office there'll be little chance of post-election war-crimes trials.

Who did what and why?