Most major media in the United States has given up on covering politics as if it mattered. From talk radio to talk television to the Washington bureaus of too many of our dying newspapers, the coverage of the 2010 election cycle is framed in one of two ways:

A. A fight between conservative Republicans and liberal Democrats. B. A fight between conservative Republicans and Tea Party Republicans to decide who will get to vanquish the liberal Democrats in November.

What’s missing from this calculus is the reality that this is an exceptionally volatile moment economically, socially and politically in the United States — a moment so volatile that both major parties are experiencing unprecedented turbulence within their ranks.

The first partisan primaries, last month in Illinois and this week in Texas, have seen intense multi-candidate contests for key nominations on both sides of the ballot. Incumbents are facing fights within their own parties, open seats are attracting contenders from all wings of the two major parties, and independent and third party contenders are waiting in the wings.

This is a year that will be packed with ideological sparring and nuanced messaging on all sides.

It is absolutely appropriate, for instance, to highlight the Florida fight between Governor Charlie Crist and former state House Speaker Marco Rubio for the Republican nomination to fill an open U.S. Senate seat representing that state. Crist is a relative moderate who has actually had a few nice things to say about President Obama and who might serve in the Senate as someone seeking bipartisan agreement; Rubio is a hardliner who errs right on every issue. Their primary contest is a great one.

But it is not the only one.

In fact, Democrats will have as many serious primary contests for House and Senate seats this year as Republicans, and perhaps more. In California, for instance, progressive leader Marcy Winograd has mounted such a serious challenge to conservative Democratic Congresswoman Jane Harman that Winograd is now being attacked by party leaders who are unsettled by the prospect that her anti-war, anti-Wall Street, pro-civil liberties candidacy might upset the incumbent.

Similarly intense contests have developed for Senate seats in Pennsylvania and Colorado, with incumbents Arlen Specter and Michael Bennet both facing tough challenges from credible challengers. (The Pennsylvania race between Specter and Congressman Joe Sestak is less of a left-right battle, especially since Sestak has tacked well to the right on foreign policy; but the Colorado contest offers a clear choice between a corporation-friendly centrist incumbent who polls very badly and a populist challenger, former state House Speaker Andrew Romanoff, who polls far better against Republican prospects.)

Now, however, what could be the most interesting and important primary fight on the Democratic side has developed in Arkansas.

Senator Blanche Lincoln, the exceptionally uninspired (and uninspiring) Arkansas Democrat who has dragged her heals on health-care reform, labor-law reform and just about every other major issue that matters to grassroots Democrats while at the same time backing bank bailouts and trade policies that batter Arkansas workers and farmers, will face a serious primary challenge from the state’s lieutenant governor.

Bill Halter, who was elected to Arkansas’ No. 2 job with 57 percent of the vote in 2006, has positioned himself as a far more progressive player on education, health care and, above all, economic issues than Senator Lincoln.

That’s got a frightened Lincoln trying to portray the Halter challenge as an "extremist" assault on her by the left-wing blogosphere. Halter’s certainly got a lot of online backers.

MoveOn.org was quick to celebrate the "huge news" that Halter was running.

A MoveOn blast issued mid-day Monday asked:

Just how bad is Blanche Lincoln? She promised to filibuster any health care bill that included a public option after taking more than $866,000 from insurance and HMO interests. She’s the #1 recipient of campaign contributions from Big Oil in the last year, and now she’s sponsoring a bill to roll back the Clean Air Act. And she accepted more than $1.3 million over her career from Wall Street banks and financial interests, and then voted to kill legislation that would’ve allowed struggling homeowners to renegotiate their mortgages and stay in their homes. Here’s how MoveOn member Jennifer P. from Little Rock put it: "Lincoln never met a special interest she didn’t like. It’s hard to express just how awful she has been as a senator. I don’t know of anyone who will vote for her if she shows up on the November ballot." That’s why MoveOn members in Arkansas voted 92% to support Halter’s campaign to replace her. Fortunately, we’ve got a much better alternative. Bill Halter has a progressive record as lieutenant governor and he’s willing to take on big corporations when he gets to Washington.

Bloggers Glenn Greenwald and Jane Hamsher, the co-founders of Accountability Now PAC, were just as fast in rallying their readers and allies to back Halter: "We’re proud to announce our first candidate: Arkansas Lieutenant Governor Bill Halter will challenge Blanche Lincoln in the Democratic primary for her Senate seat. Lincoln is at the front of the line when it comes to using her power in the Senate to repay her corporate donors with political favors. Now’s our chance to hold her accountable."

The online support should help Halter fill his coffers as he seeks to compete with the more than $5 million — much of it special-interest money that Lincoln has on hand for this year’s race.

But Halter’s is much more than an internet-generated candidacy. In fact, if it was just that it would be easily dismissed in a state where Democratic primaries are still decided county-by-county, precinct-by-precinct, by party loyalists and voters who have traditionally been cautious about taking cues from outside groups or backing candidates they do are not sure "get" Arkansas. (Remember that Barack Obama fared poorly against former Arkansas First Lady Hillary Clinton in the 2008 Arkansas Democratic presidential primary, just as he lost there to Republican John McCain in the fall.)

Halter’s viability has everything to do with his record on the ground in Arkansas.

For instance, against the counsel of those who said the state would not take the necessary steps to expand access to higher education, Halter helped organize and then led a campaign to establish a state-run lottery that would direct all proceeds to scholarships for Arkansas citizens to attend Arkansas colleges. Halter’s campaigning helped qualify a constitutional amendment for the state ballot and then got it passed by a remarkable 2-to-1 margin.

A former economic adviser to President Clinton who went on to lead the Social Security Administration, Halter knows Washington as well as Lincoln. But, unlike the incumbent, he clearly recognizes that Washington is broken.

"Washington is no longer on the side of Arkansas families," declares the Democratic lieutenant governor, whose announcement video strikes a decidedly populist tone.

"Washington is broken — bailing out Wall Street with no strings attached while leaving middle-class Arkansas taxpayers with the bill; protecting insurance company profits instead of protecting patients and lowering health costs; gridlock, bickering and partisan games while unemployment is at a 25 year high," says Halter. "Enough’s enough…"

That’s an old-fashioned populist appeal, as old-fashioned as Halter’s bashing of "Republican and Wall Street schemes to privatize (Social Security)."

But old-fashioned populism is the only message that will keep Democrats competitive in states such as Arkansas — which, it should be noted, has a long history of seeing Democratic senators challenged in primaries, and (in the classic case of the 1974 Bill Fulbright-Dale Bumpers contest) beaten.

The fight for the soul of the Democratic party in a moment when too many D.C. Democrats are acting as managers rather than leaders will not stop at the Arkansas border, however. The Halter-Lincoln contest has the potential to send signals to states far to the north and west of Arkansas — and all the way to Washington.

This is what makes Halter’s challenge to Lincoln in the state’s May 18 primary — a relatively early one on an election calendar that won’t see California vote until June, Colorado until August and 11 states until September — so significant, and potentially so definitional for Democrats.