After Tuesday, one-fifth of the 2010 primaries will be done.

We’re deep into the election cycle.

So where are the fireworks?

They promised us fireworks.

Does the show begin tonight?

Maybe. Then again, maybe not.

So far, the 2010 election cycle has added up to lots of hype and very little in the way of change.

Despite all the media focus on the Tea Party movement, Republican candidates who aligned with it fared poorly in the Illinois, Texas, Ohio, Indiana and North Carolina. For the most part, establishment contenders have won key U.S. Senate, U.S. House, gubernatorial and statewide constitutional races.

In Texas, where Tea Party activists made a big play for state legislative seats, they generally failed.

In fact, there has been more churn on the Democratic side. The only member of the House to be defeated in a primary thus far is West Virginia Congressman Alan Mollohan, a relatively mainstream Democrat with ethics troubles who got beat in his May 11 primary by a relatively mainstream (if slightly more socially-conservative) Democrat with a reform message, Mike Oliverio. (Utah Republican Senator Bob Bennett also appears to be out of a job and he really was targeted by the Tea Party crowd; but he got beat at a closed state convention rather than in a primary.)

Tuesday’s round of primaries in Arkansas, Kentucky, Oregon and Pennsylvania should give a clearer indication of the extent to which voters are in an anti-incumbent mood. Two incumbent Democrats senators, Arlen Specter in Pennsylvania and Blanche Lincoln in Arkansas, face vigorous challenges, while a third, Oregon’s Ron Wyden, could be embarrassed if a significant protest vote is cast against him.

Additionally, Kentucky has intense primary contests on the Democratic and Republican sides for an open Senate seat. And there are various and sundry U.S. House, gubernatorial and statewide and legislative contests that will provide signals.

What are the prospective scenarios?

Beginning with the most interesting one, they go like this:

GOT A REVOLUTION! GOT A REVOLUTION! Two senators lose: Pennsylvania’s Arlen Specter and Arkansas’ Blanche Lincoln lose. Almost as significantly, Oregon Senator Ron Wyden loses a substantial portion of the vote—over 25 percent—to self-described “conservative Democrat" Loren Hooker, who has received some support from Tea party activists. In Kentucky, Republican Rand Paul, the relatively libertarian, relatively anti-interventionist son of Texas Congressman Ron Paul, and Democrat Dan Mongiardo, a populist much disliked by the party establishment, win their Senate primaries. And in a Pennsylvania House race, Republican Tim Burns takes the Democratic seat of the late Congressman Jack Murtha. Toss in a couple of upsets in gubernatorial and down-ballot races and you’ve got everything you need to speculate about 2010 being another 1994—or at least a 1978 (a year when Republicans won enough off-year races to signal that then-President Jimmy Carter’s number was up.)

GOT NO REVOLUTION? GOT NO REVOLUTION! Specter and Lincoln beat back credible challengers with relative ease, Wyden wins without a sweat. Kentucky picks party favorites Jack Conway for the Democratic Senate nomination and Trey Grayson on the GOP side. And the Murtha seat stays Democratic, albeit in the hands of former Murtha aide Mark Critz, who did not exactly run against President Obama but most definitely ran away from him. That doesn’t matter much, however, as the Murtha district never liked Obama anyway—it voted for Hillary Clinton in the 2008 Pennsylvania presidential primary and for Republican John McCain in the fall.

This is the incumbents-can-pop-some-champagne corks result, especially if the turnout on the Democratic and Republican sides in the various primary states follows patter. (Note: A big bump in Republican turnout would be significant, as it might suggest a more motivated base; conversely, unexpectedly high Democratic primary voting—as we saw earlier this month in North Carolina—could further confirm that the Tea Party talk is just that: talk.

UPHEAVAL, MAYBE, BUT NO REVOLUTION: Specter loses, Lincoln wins, or vice versa. Wyden does fine. No House incumbents are upset. The Murtha seat stays Democratic. But Paul wins the GOP nod in Kentucky and the Tea Party influence is felt in the Oregon Republican gubernatorial primary.

This would be the sort of mixed result that everyone will try to spin but that, in reality, will suggest that 2010 could be a less volatile year than is generally anticipated. The key word, of course, is “could.”

There will be more primaries—particularly in California in early June, where there are rollicking Republican primaries for governor and U.S. Senate and where the L.A. congressional race between Democratic incumbent Jane Harman and progressive challenger Marcy Winograd keeps getting hotter. And we’ll all keep looking for the evidence that this is going to be a year of fireworks or, perhaps, that the show has been postponed until 2012.