Editor's note: John P. Avlon is a CNN contributor and senior political columnist for The Daily Beast. He is the author of "Wingnuts: How the Lunatic Fringe is Hijacking America."
New York (CNN) -- On Tuesday, 12 states will turn out to vote in primaries -- settling the midterm general election slates for one-quarter of the USA, stretching from the East Coast to the West.
The battle lines are drawn between the embattled centrists and the enraged base in both parties. We've seen a flurry of RINO hunting and DINO hunting so far this year, successfully targeting incumbents who are derided as "Republicans in Name Only" or "Democrats in Name Only," deemed to be insufficiently ideological by grass-roots activists and their backers.
The BP oil disaster only strengthens populist anger at both big business and big government to date. And this year's intra-party purification debates continue unabated.
Closed partisan primaries are a paradise for party activists, but they can lead to a vicious hangover the morning after, as parties begin to wake up to the reality that principled centrists generally have a better chance to win a general election than those from the ideological extremes.
So think of this column as your pregame look at the candidates in the big-stakes states, starting with California and working our way to South Carolina.
The nation's most populous state has been wrestling with a fiscal apocalypse that even its action-star Gov. Arnold Schwarzenegger hasn't been able to tame, despite a series of emergency budgets. Nonetheless, candidates have spent upwards of $100 million for the privilege of succeeding him in the Sisyphean position.
On the right, the battle has been between eBay billionaire Meg Whitman and State Insurance Commissioner Steve Poizner, himself a self-funded Silicon Valley alumnus. Whitman has the potential to be the face of a rebranded GOP, a pro-business centrist on social issues, who promises to bring executive management to the Golden State.
But Poizner has attempted to attack her right flank (despite the fact that he was a former Al Gore donor) depicting Whitman as liberal and soft on immigration -- bringing him within striking distance in a poll a few weeks ago. Whitman has now steadied herself and seems to be in pole position.
The winner is likely to face former Gov. Jerry Brown, who since a 1992 run for president has remade himself after successful stints as mayor of Oakland and the state's attorney general.
In the U.S. Senate primary, former Hewlett-Packard CEO Carly Fiorina is squaring off against centrist former Rep. Tom Campbell and conservative state Assemblyman Chuck DeVore for the privilege of running against the surprisingly vulnerable liberal three-term incumbent Barbara Boxer.
But the most potentially game-changing item on the ballot will get the least attention: a referendum called Proposition 14, which would make all future primaries open and nonpartisan, fully enfranchising the state's millions of independent voters and making it less likely that pandering to the partisan extremes will dominate the election process and lead to inevitable gridlock.
Next to Nancy Pelosi, Harry Reid is the face of the Democratic majorities that control Congress, which are currently less popular than George W. Bush was when he left office. In the swing state of Nevada, Reid is vulnerable, especially when seen in the light of previous Democratic Party leaders who've lost their seats, like Tom Daschle.
But Harry Reid has been given an unexpected gift from an unexpected source -- the Tea Party. They've put forward their own primary challenge to the GOP establishment nominee, former state Sen. Sue Lowden -- a conservative insurgent candidate named Sharron Angle, who had previously served in the state assembly.
Lowden wasn't helped when she appeared to long for the days when people bartered for doctors' bills with chickens as an alternative to Obama's health care reform, and Angle's campaign received a boost from endorsements by radio show host Mark Levin and the Tea Party Express. This race is neck and neck, but the beneficiary of the GOP blood-letting might just be Reid.
Sen. Blanche Lincoln has been a steadfast centrist in the U.S. Senate, working with the likes of retiring Sen. Evan Bayh to forge something like consensus around fiscal responsibility. Unfortunately, the center is a demilitarized zone in the Senate, and Lincoln has come under fire not only from her Southern state's conservatives, but also from the liberals, who consider centrists "corporate sellouts."
"Big Oil Blanche," as she's being called in the wake of the BP oil spill, is in a tough run-off against state Lt. Gov. Bill Halter -- it's MoveOn.org versus the Chamber of Commerce. A prominent endorsement by favorite son Bill Clinton has helped Lincoln, but Halter's been aided by a flood of money from labor organizations, which Lincoln alleges exceeds $2.5 million. Lincoln has been under fire for receiving hundreds of thousands of dollars in campaign contributions from people associated with the oil and gas industry, while labor is angered by her opposition to card check, a measure to speed the organizing of unions.
The most recent polls show Halter leading Lincoln by four points, a sign of the emerging DINO-hunting impulse in the Democratic Party. Complicating the picture are polls that show Lincoln the more competitive general election candidate against the likely GOP nominee.
The race to succeed Gov. Mark Sanford has somehow gotten more sordid than the fallout from his trip down the Appalachian Trial via Argentina. Thirty-eight-year-old Nikki Haley catapulted into the lead of a crowded field after an endorsement by Sarah Palin, proving the Alaskan's influence among Southern conservatives. But the fiscally conservative Indian-American legislator Haley's Cinderella story hit a snag when not one but two local political operatives claimed to have had short-lived affairs with her.
The married mother of two promptly denied all accusations and accused her rival, Lt. Gov. Andre Bauer, of being behind the smears. The campaign got even uglier after state Sen. Jake Knotts said, "We've got a raghead in Washington, we don't need a raghead in the Statehouse," referring to Haley's Indian ancestry.
Lost in the avalanche of innuendo is the candidacy of South Carolina Attorney General Henry McMaster, an honorable long-time local official. We'll see if there's a run-off, but Haley is polling as much as 20 points ahead.
That's not all -- there are gubernatorial and congressional primaries in Iowa, Maine, Montana, New Jersey, North Dakota, South Dakota and Virginia on Tuesday. It's the true small super Tuesday of the 2010 cycle -- and when it's over we'll get the clearest sense yet of the field in what is shaping up to be the most consequential midterm election since the Newt Gingrich-led Republican Revolution of 1994.
It is premature to speak of lessons learned before the votes are cast. But one likely result of the RINO-hunting and DINO-hunting are parties that are less likely to win come the fall unless their candidates face an equal and opposite extreme or engage in a thorough demonization of their opponent.
The logical result of this path is parties that are even more polarized, even more ideologically invested in partisan gridlock. While centrists might find themselves under attack in closed partisan primaries, the parties and voters alike should see that they not only offer the best chance of victory, but also the best chance of achieving stable solutions and even civility.
The opinions expressed in this commentary are solely those of John P. Avlon.