While the Tea Party folks have gotten a lot of attention from the media in the Republican primaries so far, there are a few Democratic primary races which may have just as interesting an impact on the Democrats as the Tea Party challenges are having for Republicans. And since last week I took a look at the effect of the Tea Partiers in Republican races, today I thought it would be worth paying some attention to the Democratic side of the aisle. Because the anti-incumbent "throw the bums out" feeling seems to be happening to some degree in both parties this year. What it all means for the general election remains to be seen, of course. For now, let's take a look at a handful of these upcoming primary races.

Pennsylvania (Senate)

The first of these races is the most unique, since Senator Arlen Specter of Pennsylvania hasn't been a Democrat all that long. Specter jumped the aisle to become a Democrat when it became increasingly clear that he didn't have a chance to win the Republican primary against Pat Toomey. Specter beat Toomey's primary challenge the last time Specter was up for re-election, when they were both Republicans, but only by the skin of his teeth (by a margin of 17,000 votes). And Specter was pretty obvious, when making the party switch, that a large part of why he was doing so was that it was the only way he could keep his job. If he had faced Toomey in a Republican primary this year, Specter likely would have been crushed.

But Specter, although given a free pass from leading Democrats as part of the price for his party switch (President Obama and other Democrats have supported Specter), Representative Joe Sestak did not go along with this deal. He's running as the "real Democrat" in the race, and making much political hay over Specter's political opportunism. And it appears this message is beginning to work, especially after Sestak ran a strong television ad pointing it out in no uncertain detail. The last two polls released for the Pennsylvania Democratic primary show Sestak with a four or five point lead over Specter -- which he hasn't managed to do until now. Now, both polls had a fairly small sampling (around 400 "likely voters"), meaning that the margin of error is higher than normal. But Sestak does seem to be gaining momentum, so it is possible that he could beat Specter in the primary to face Toomey in November. Specter faces a potential problem this summer as well, with President Obama's Supreme Court pick, since (when he was a Republican) Specter voted against confirming her to the job she now holds -- meaning Specter is going to have to explain either why he's about to flip-flop and support her, or why he's going to vote with Republicans not to confirm her. Neither of these positions is likely to win him a lot of Democratic voter support. All in all, Sestak may have the best chance of any Democratic primary challenger who is taking on a sitting senator this year.

Both Specter and Sestak poll similarly against Toomey, but the bad news is that they both poll about ten points behind Toomey. It may not matter which one of them wins the Democratic nomination, if Toomey wins the general election. The choice for Pennsylvania Democrats is going to be which of the Democratic candidates would have a better chance against Toomey.

Pennsylvania's primary will take place next Tuesday.

Arkansas (Senate)

Senator Blanche Lincoln, unlike Arlen Specter, was never formally a Republican, but she is one of the bluest of Blue Dog Democrats (or perhaps "one of the doggiest"... not sure how that metaphor breaks down, personally) in the Senate, and she is being targeted from her left in the Democratic primary in Arkansas. Her challenger is Bill Halter, who has received a lot of support from Big Labor, because they are absolutely incensed at Lincoln for repeatedly voting against their interests in the Senate, which included her being one of the obstructionist Democrats in the health reform battle.

Halter isn't any sort of "far left" candidate, but Big Labor doesn't particularly care about the details, as they are not only looking to take Lincoln down, but also to use the race as a serious warning to other Democratic officeholders. Expressed in clear language, this warning might be worded: "Do not take Union support for granted -- if you work against our interests, then we will work against you." So far, they have pumped a million dollars into Halter's race, and could spend even more by the time it is over. Lincoln still has a comfortably large campaign chest of her own, however, but the ad wars on the airwaves are getting pretty brutal in Arkansas.

So far, if the polls are correct, Lincoln has been doing a fairly good job of shoring up her base support in the primary. She's got a healthy double-digit lead over Halter so far, and even the flood of Union ads on his behalf hasn't beefed his numbers up much. Unions have never had an enormous presence in the state, which is home (after all) to Wal-Mart. And with time fast running out, it looks like Halter will fall short of his effort to unseat this particular Blue Dog.

But the real bad news for Democrats is that this race may be the Republicans to win, no matter which Democrat they have to run against in the general election. Lincoln's approval ratings are pretty dismal in the state, and in head-to-head matchups, neither Lincoln nor Halter are even close to their Republican opponent -- both poll significantly lower, sometimes over 20 percent lower. Meaning the Democratic primary may (other than sending a Big Labor message to other Democrats) ultimately be meaningless this year.

Arkansas' primary will also take place next Tuesday.

Colorado (Senate)

The third sitting Democratic senator having problems from within his own party is Michael Bennet in Colorado. Bennet was not elected to his Senate seat, he was appointed to fill the vacancy left when President Obama named Ken Salazar as his Secretary of the Interior. So Bennet doesn't really have a long history of being a national officeholder from his state to fall back on.

A former Democratic speaker of Colorado's House, Andrew Romanoff jumped into this race even though national Democrats (all the way up to the White House) tried to clear the primary field for Bennet. A recent quote from Romanoff pretty much sums up not only his reason for running, but also a lot of voters' frustration: "It is not only the stubbornness of Republicans that's at fault here; it is too often the spinelessness of Democrats."

Colorado doesn't have a lot of polling numbers available, so it's really anybody's guess what will happen in the primary. A poll two months ago showed Bennet over Romanoff by six points, but at 40-34, this still leaves a lot of undecided voters in the mix. At this point, the race is truly a tossup. Both Bennet and Romanoff do about equally well against the likely Republican nominee, but the bad news is that both are polling about seven points behind Republican Jane Norton.

Colorado could actually become the most interesting race in the nation this November, if both sides split their support into a true four-way race. In essence, voters would get the chance to choose between two Democrats, and two Republicans. Meaning it may be a real free-for-all type of race.

Colorado's Democratic state convention will be on May 22.

Hawai'i (House)

One House race is worth mentioning here as well, from Hawai'i, because a lot of people are going to read far too much into the tea leaves of the upcoming special election here. A Republican is likely to win, which will lead some to anoint him as the next Scott Brown, ushering in an era where Republicans take Democratic strongholds like Teddy Kennedy's Senate seat, and the home district of Barack Obama (by a very loose definition of "home"). Ironically, this could actually help the Democrats in November, in a tiny way. Which is why I say the pundits are likely going to get this one wrong.

This fracas all got started when longtime Democratic Congressman Neil Abercrombie stepped down from his House seat to run for governor. Because he resigned his seat, Hawai'i is holding a special election to fill it. But special elections have no primary. So two very strong Democratic candidates wound up on the ballot, and only one strong Republican candidate. Neither Democrat is going to back down and hand the seat to the other, which means even though Hawai'i is overwhelmingly Democratic, the Republican could easily win in this three-way race (it's actually a lot more than "three," but there are really only three strong contenders in a wide field of candidates on the ballot).

So, if the pundits were smart, they'd compare this race to what happened in a special election in New York's 23rd congressional district, but more than likely if Republican Charles Djou wins, people will be proclaiming him "the next Scott Brown."

He'd better enjoy this while it lasts, because it likely will not last very long at all. Because, as with all House seats, he'll be up for re-election in less than six months. And in November's election there will be a primary, so he'll only be facing one Democrat. Who will, most likely, win.

The recent news from this race looked grim, as the national Democratic Party itself just threw up its hands and decided to pull their money out of the special election, and let the chips fall where they may. But even if the Republican wins later this month, look for both Democrats to re-file for the real 2010 race, where they will have an orderly primary to decide which of them will have the honor of winning the seat back for the Democrats.

As I said, in a tiny way, this is going to help Democrats this November. Because there aren't going to be a whole lot of races where Democrats defeat incumbent Republicans in the House (according to most estimates), so this will most likely be at least one bright spot in the election returns later this year for Democrats.

Hawai'i holds its special House election on May 22, the filing date for the regular election is July 20, and the primary for the regular election is September 18.

Conclusion

While groups on the Left haven't captured the attention of the mainstream media the way the Tea Party faction has over on the Right, they are equally serious about challenging sitting members of Congress on their side of the aisle in the primary season, at least in a few places. After watching the Blue Dogs push the entire Democratic Party around in the health reform debate, some on the Left feel that it's time to get some authentic Democrats into office to replace people who just seem to have a "D" by their name as some sort of convenience.

But ousting sitting members of Congress (especially senators) is not an easy task, even in an anti-incumbent year. The real question, as on the Right, is whether officeholders will attempt third-party independent (or even write-in) campaigns in the general election, in a last-ditch effort to keep their job. Joe Lieberman proved it can indeed be done successfully, and Charlie Crist may be about to prove the same thing from the Republican side in Florida. Arlen Specter has already changed parties once, so it's not too much of a stretch to imagine him attempting to run under no party banner if he loses to Sestak. He might even have a better chance in a three-way race. So might Blanche Lincoln, if the polls turn out to be wrong and if she is beaten by Halter next week. Bennet is already collecting signatures, in case this is the only way to get his name on the ballot.

One thing which has been proven already -- to both parties -- is that this is not the year to take your "base" for granted. There are a lot of very angry voters out there (for various different reasons) who are looking to purge the two parties of those deemed insufficiently pure. While this may only affect a few seats come November, it still puts a healthy fear into every officeholder to placate their own voters. Even if the effect is just a message sent by base voters to national party leaders, I think all politicians are going to be a lot more cautious in what they vote for (and against) for the remainder of this year, at least. Because the biggest message is that voters are not in any kind of forgiving mood this time around.

Cross-posted at The Huffington Post

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-- Chris Weigant