Tuesday’s round of primaries and special elections was pretty momentous, though the chattering classes continue to argue over their larger meaning, if any.

In Pennsylvania, Rep. Joe Sestak edged incumbent, party-switching Sen. Arlen Specter, ending his long and contentious political career. More exciting to political junkies was the relatively easy Democratic victory in a special election in the twelfth congressional district, in Western Pennsylvania, which Republicans had expected to win. Depending on your point of view, this result either meant that Republicans aren’t going to win the kind of landslide in November that so many have predicted, or that Democrats have to separate themselves from the Obama agenda to survive. Meanwhile, in a very low-key primary, Allegheny County Executive Dan Onorato won the Democratic gubernatorial nomination, and begins the general election as an underdog against Republican Attorney General Tom Corbett.

In Kentucky, of course, Rand Paul trounced Secretary of State Trey Grayson, Mitch McConnell’s protégé, for the Republican nomination to succeed Jim Bunning, and instantly became the national symbol of the Tea Party. Attorney General Jack Conway’s strong showing in the Louisville area helped him edge Lt. Gov. Dan Mongiardo for the Democratic nomination in a race largely devoid of substantive differences between the candidates.

In Arkansas, after an expensive campaign all but dominated by out-of-state interests, labor-backed Lt. Gov. Bill Halter forced business-backed Sen. Blanche Lincoln into a runoff three weeks from now.  A third candidate, the very conservative D.C. Morrison, took 13 percent of the vote but refuses to endorse either candidate in the runoff.

And in Oregon, former Gov. John Kitzhaber easily won the Democratic gubernatorial nomination over former Secretary of State Bill Bradbury, while former NBA player Chris Dudley beat conservative activist Allen Alley for the GOP nod.

This has been a very active week for political pollsters. One of the most controversial surveys was, typically, done by Rasmussen, which did a snap poll after the Kentucky primaries and showed Rand Paul with an astonishing 25-point lead over Jack Conway, for a deconstruction of this survey, see Nate Silver.

The Public Policy Institute of California released a major new poll this week, showing a competitive Republican gubernatorial race between former eBay CEO Meg Whitman and Insurance Commissioner Steve Poizner. Whitman has already spent $68 million on her campaign so far, and Poizner’s spent $24 million; their highly negative attack ads against each other are dominating the California airwaves. Meanwhile, Democratic candidate Jerry Brown has moved ahead of both Republicans in PPIC’s general election trial heat. PPIC also showed a close three-way race for the Republican Senate nomination in California, as former Rep. Tom Campbell and former Hewlett Packard executive Carly Fiorina fight for the lead, while conservative hard-liner Chuck DeVore moves up rapidly into contention.  Barbara Boxer, meanwhile, has re-established a lead over all the GOP candidates.

Rasmussen conducted the first poll in several months of the very competitive South Carolina Republican gubernatorial primary, indicating that right-wing favorite Nikki Haley, who trailed the field initially, has leapt into the lead, with Attorney General Henry McMaster, who is the closest thing to a moderate in the race, running second. Controversial Lt. Gov. Andre “Stray Animals” Bauer is running last, with high unfavorables. In a separate poll, Rasmussen found Rep. Vincent Sheehan now running ahead of early front-runner and State School Superintendent Jim Rex in the Democratic gubernatorial contest in South Carolina. Both contests could well be heading for runoffs.

Next door in Georgia, Insider Advantage’s poll of the Republican gubernatorial race shows little change from earlier surveys: State Insurance Commissioner Jim Oxendine leads the field, while former U.S. Rep. Nathan Deal and Secretary of State Karen Handel are battling for second place.  Many Democrats are hoping that Oxendine and Deal, both of whom have been struggling with ethics charges, wind up in a runoff.

And finally, the first post-primary poll in the Pennsylvania Senate race, again by Rasmussen, shows Democrat Joe Sestak running ahead of former U.S. Representative and Club for Growth president, Pat Toomey by four points. This is the first time in many months that Toomey has trailed any Democrat in general election polls, and a very good sign for Sestak.