Americans are casting ballots Tuesday in an off-year election that could provide a revealing glimpse of the public's mood as the 2012 electoral campaign kicks into high gear. Are voters in crucial swing states showing a preference for Democrats or Republicans? Which contests will shed light on President Obama's chances of beating the ultimate GOP nominee? Here, four key questions to consider:

1. Where is Ohio leaning?
On Tuesday, the Buckeye State will decide the fate of Republican Gov. John Kasich's controversial anti-public union bill. Polls suggest Democrats will score a big win on this referendum, with 59 percent saying they'll vote to repeal Kasich's bill, SB-5. In 2010, Republicans seized control of state governments in Ohio, Wisconsin, and Michigan, and quickly passed bills limiting public-union bargaining power. But in Ohio, Democrats managed to keep the measure from taking effect by putting it to a referendum. And if the Left wins on Tuesday, says Eric Kleefeld at Talking Points Memo, it may mean "a possible resurgence" for Democrats in a "major swing state."

2. Will other battleground states tip their hands?
The legislatures in two other important swing states — Iowa and Virginia — could flip from Democratic to Republican control on Tuesday. The GOP has "numerous pathways" to seize a majority in Virginia's state Senate, say Julie Sobel and Sean Sullivan at National Journal, which would give the party complete control of the state government. Obama handily won the Old Dominion State in 2008, and "if Virginia turns completely Republican," says Patrick O'Connor in The Wall Street Journal, "it may not bode well for Obama's chances there next year."

3. Who will win the next battle in Arizona's immigration war?
Arizona's showdown over illegal immigration gets personal on Tuesday, as opponents of the state's controversial crackdown try to recall the chief architect of the bill, state Sen. Russell Pearce (R). Will Pearce's fate "send a powerful message to the legislature that uncompromising stands on immigration and other issues will not be tolerated by voters," says Fox News Latino, or will Arizonans prove that "a tough stance on illegal immigration is just what voters demand"?

4. Will the abortion debate be forever changed?
A ballot initiative in Mississippi defining "personhood" as beginning the moment a human egg is fertilized is widely expected to pass. The measure would ban abortion, and even make certain forms of birth control and fertility treatments illegal. Even if this initiative passes, it will almost certainly face court challenges, and potentially wind up before the U.S. Supreme Court. So no matter which way Mississippi goes, says Irin Carmon at Salon, the state will "reshape the abortion debate" with Tuesday's vote.