If you've used Facebook today, you've probably already seen it: a big red-white-and-blue election button at the very top of your news feed. Within Facebook, it's known as the voter megaphone, and this year, the company is rolling it out to every US citizen over the age of 18. But while Get Out The Vote efforts are usually seen as apolitical, Facebook's program has drawn a surprising amount of controversy in the run-up to today's elections.

It started on Friday, when Mother Jones ran an exclusive look into the technology behind the megaphone. The 2012 megaphone had been inconsistent, thanks to some software bugs, and didn't end up reaching everyone. At the same time, Facebook had been running another newsfeed experiment, giving news stories an algorithmic boost for certain users to see if it heightened civic engagement, as measured by a questionnaire. In both cases, the net effect should have been more voters across the board, but the combination has raised criticism about the potential political effects of Facebook's voter efforts. What if the push sent more Democrats than Republicans to the polls, shifting the balance of a swing election? What if that power ends up being leased out as part of Facebook's advertising goals? Are we entering the next era of socially networked campaigning?

Facebook, for its part, has maintained that all it wants is to get people to the polls. "Our effort is neutral," said a company spokesperson, "while we encourage any and all candidates, groups, and voters to use our platform to engage on the elections, we as a company have not used our products in a way that attempts to influence how people vote." The megaphone button has appeared in US elections since 2008, as well as national elections in India, Brazil and Indonesia, but thanks to the fix for a previously unpredictable algorithm, this is the first time the company is sure it's reaching everyone of voting age on the network.

The news feed experiment is more sensitive. Facebook drew criticism this summer for altering user feeds as part of a psychology experiment, and ultimately implemented new research guidelines as a result of the controversy. The company says the 2012 experiment is consistent the new guidelines, and is set to be published later this year, but Facebook emphasized that it wasn't boosting any partisan messages, only general news content. Still, when researchers from UC San Diego conducted a similar study during the 2010 elections, they found a slight social nudge can have a big impact. After sending randomized messages over Facebook, "the results show[ed] that the messages directly influenced political self-expression, information seeking and real-world voting behavior of millions of people."

In other words, Facebook is already a powerful political tool, however it ends up being used. That's not terribly surprising by itself — there are hundreds of political science studies about the importance of social connection in voting behavior — but it suggests the platform itself is emerging as a new political force. It's easy to imagine a time when Facebook outreach is as important to a campaign as town hall meetings or television ads. Would that be more democratic or less? If the critics seem worried, it may be because it's too early to tell.