The polls are now open in Wisconsin for the big event: Six recall elections targeting incumbent Republican state senators, in a backlash against Gov. Scott Walker's anti-public employee union law and other budget decisions, with the potential for control of the state Senate to be flipped to the Democrats after just seven months of one-party GOP government.

The polls opened at 7 a.m. CT, and will close at 8 p.m. CT. Under Wisconsin's recall laws, these elections are effectively special elections, with the incumbents each facing a Democratic challenger in a head-to-head race. And given the unusual nature of these races, it is nearly impossible to predict who will win, with everything riding on turnout.

As the Milwaukee Journal Sentinel reports, the state Government Accountability Board has declined to make any turnout predictions, as they would normally do, because of the lack of any statistical precedents. On the other hand, as just one anecdotal example, the city clerk in Fond du Lac (where GOP state Sen. Randy Hopper is on the ballot against Democratic candidate Jessica King) predicted that turnout could go as high as 75%-80% of registered voters — comparable in that area to a gubernatorial race — based on the volume of calls, voter registrations and absentee ballot requests.

So while there has been polling showing many of the races close, and WisPolitics has some very well educated ratings for the six races, even these too must be taken with some caveats, as only the best possible attempts at a very difficult problem. In the end, the only real proof will be the in the actual votes.

It is also important to keep in mind that all six of these districts are, on paper, serious uphill climbs for Democrats. The incumbents were last elected in 2008, winning their districts even in the middle of the huge Democratic wave that year.

The state Senate currently has a 19-14 Republican majority, with Democrats needing to gain at least a net three seats to gain control on the senate. (And even this would not be the end of it. Democrats hope to recall Walker some time next year — but would first have to be successful today in order to have any momentum.) All in all, this is the closest this country's system of government can get to a snap parliamentary election, with control of the chamber up for grabs.

Also, even if Democrats pick up as many as four seats Tuesday, it would not be known for certain whether they have gained the chamber until next week, when two Democratic incumbents face their own recalls. Back in July, Democratic state Sen. Dave Hansen easily won re-election in his recall race against a very flawed GOP challenger, after the party's originally recruited candidate failed to collect enough valid petition signatures to get onto the ballot.

With that said, the political stakes are enormous. As noted above, Democratic success in these recalls could compound the momentum for an attempt to recall Walker in 2012 — while a Republican victory, if that were to occur, would be widely interpreted as a sign that Walker is politically secure and has sufficient approval in the state to keep pursuing his policies. Indeed, Republican state Senate Majority Leader Scott Fitzgerald cast the recalls as a "referendum" on whether Wisconsin, and moreover other states, will follow the same course as Walker.

With so much on the line, tens of millions of dollars have been spent on these races, an extraordinary amount for these Midwestern state legislative seats. Simply put, there is a lot riding on these elections for both the left and right, and it's anybody's guess who will win.

Republished with permission from TalkingPointsMemo.com. Authored by Eric Kleefeld. Photo via AP. TPM provides breaking news, investigative reporting and smart analysis of politics.