GOP candidates for U.S. Senate, from left, Todd Young, Marlin Stutzman and Eric Holcomb debate in January in Indiana. Holcomb has since dropped out. Young spoke with authority on foreign policy and his experience in the Marines. (Tim Bath/Kokomo Tribune via AP)

In Indiana, there's some unexpected electoral drama for the state's open Senate race.

GOP Rep. Todd Young, the favorite and establishment pick, appears to be in some danger of not qualifying for the Republican primary ballot. If he doesn't make the ballot, it would likely hand the nomination to a more conservative candidate, GOP Rep. Marlin Stutzman, and potentially put a safe Republican seat in play for Democrats.

That's a lot of "ifs," but the fact that it's even possible highlights the often-complex, error-fraught world of ballot access laws that can make or break a campaign. And relatively speaking, Indiana's rules aren't even that strict: The state requires any U.S. Senate candidate to get 500 signatures from registered voters in each of the state's nine congressional districts.

The trouble for Young lies in the state's 1st district. His campaign said he submitted nearly 650 signatures in the mostly Democratic district and that county clerks verified he had at least 500 that were valid. But Indiana Democrats announced Wednesday that they are formally challenging that number, arguing they counted just 498 validated signatures. Reports Politico's Scott Bland:

A separate report published by the Indiana Election Division showed Young perilously close to the qualification line, listing 501 signatures in the heavily Democratic 1st District. But two members of the division cautioned that their signature report is “not gospel” because of differences in the ways individual counties process and probe candidate petitions.

How to get on the ballot in the first place is one of the most-overlooked hurdles for politicians at all levels -- and if not done correctly, it can create some big problems later. Most states have some kind of petition requirement, all with varying levels of strictness. It's a process filled with human error every step of the way, and it often ends up benefiting the people in power while keeping outsiders, well, out.

We spent a few minutes chatting with electoral law expert Michael Kirkpatrick, a visiting professor at Georgetown law school, about the issues with ballot access laws in general -- including what that could mean for any independent hoping to run for, say, president. Our conversation has been edited for length.

FIX: How does Indiana's 500-signature rule to get on the Senate primary ballot compare to other states's rules?

KIRKPATRICK: This one doesn't sound particularly strict or onerous; there are certainly places where it's much harder to get on the ballot. But the rules are often extremely restrictive to get on the ballot as an independent or third-party candidate, because a lot of states have a system where if you're endorsed by a party or a party convention, it's much easier to get on the ballot. And the only people who have to go out and collect signatures are people who are outsiders trying to run as an independent.

FIX: In Indiana, it's possible election officials eliminated some 150 signatures out of 650. Is it normal to slash that many signatures? 

KIRKPATRICK: Oftentimes, large numbers of the signatures are not valid. So many candidates would always want to shoot for, like, double the number of signatures they need knowing that they could very well lose half of them if something falls through.

FIX: Why do so many signatures fall through?

KIRKPATRICK: People are maybe a little bit sloppy about collecting them -- particularly if candidates relied on paid signature collectors. A lot of times they tell people 'Hey we'll give you a dollar a signature.' So somebody might say, 'Oh I'm not registered to vote,' and they're just like, 'Uh, just go ahead and sign it,' because they want the dollar.

Carol Schwartz, right, receives the support of Vallorie Forte, 51, from Ward 7 while gathering signatures at a Safeway to get on the ballot for running for D.C. mayor in 2014.  (Astrid Riecken for The Washington Post)

FIX: It seems like the process makes it easy for the other side to cry 'Fraud!'

KIRKPATRICK: I don't think it's intentional fraud most of the time. I think sometimes people sign a ballot access petition because they're asked to outside the supermarket, and they're just like 'okay' and they may not know which congressional district they live in. And so they might make an honest mistake of signing it. And in many places you can't sign more than once, and so you're outside Safeway one day and somebody says 'Hey I'm just trying to get on the ballot, will you sign my petition,' and the same thing happens the next day. That person might have forgotten they already signed one or they might have not remembered whether what they signed was city council or attorney general.

I would imagine there are some people who just don't want to say no when somebody says, 'Hey, will you sign this? Are you a registered voter?' Maybe they don't want to say, 'Oh, I'm not a U.S. citizen' or 'I'm not registered because I have a felony conviction.' It might be embarrassing. So there could be a lot of reasons someone might just decide, 'Yeah, just give me the pen, I'll sign to make you happy and be on my way.'

It's not like going to the polls, where there's a little more uniform system for signing in and checking the rolls. It's going door to door, standing on the sidewalk. There's no verification at that point; that comes later.

FIX: Now I see why it's so hard to do this without a lot of planning and professional support. 

KIRKPATRICK: When you look at national politics, it's very, very difficult for a third-party candidate or an independent candidate to get on the ballot in all 50 states. Without having the party machinery, it can just be a very, very difficult process.

FIX: It's almost like you have to be a billionaire to even consider something like this (former New York City mayor Michael Bloomberg?).

KIRKPATRICK: Or start very, very early. Or you can be somebody like Ralph Nader, who ended up on the Green Party ticket even though he wasn't really a Green Party member. But they already kind of had an infrastructure, and so it was easier for him to get on the ballot. So unless you have a huge amount of money, it would be very, very difficult to get on the ballot as a true independent in all the states.

FIX: Is there any movement at the state level to ease ballot access laws?

KIRKPATRICK: My sense is, in most places, the status quo continues -- because the people who have the political power to make the change are people who have been successful under these rules as they stand. Then, when you do have a third-party candidacy that sort of gets some momentum, that's when you see people clamoring for changes to ballot access measures. But usually that's because there's some charismatic person like Bloomberg or Nader or Ross Perot, and they have a lot of popular support, and then there's this pressure to make those changes.

But without that I think there's just a lot of inertia on this, because the people with the political power got there under the rules as they stand, and they don't see a strong need usually to reform.