In 2006, Democrats took back control of Congress because of public outrage at George Bush and the War in Iraq. But we should remember it almost didn’t happen – until August, when Ned Lamont proved that Democrats can galvanize that energy to beat an incumbent Senator in a primary. Tomorrow, Pennsylvania Democrats will be asked to dump ex-Republican Arlen Specter – and in Arkansas, conservative Senator Blanche Lincoln also faces a primary challenge. And just like Joe Lieberman, the Party establishment is circling the wagons in both states – with President Obama shooting a radio ad that claims Lincoln “took on big insurance companies” to pass health care. A new poll shows that voters prefer Democrats over Republicans, which suggests that 2010 may not be the nightmare everyone fears. But it also showed that voters hate incumbents. If Democrats want to avoid a bloodbath in November, Specter and Lincoln must be defeated.

In a development that Democrats are celebrating, last week’s Associated Press poll found that voters prefer a “generic Democrat” over a “generic Republican” for Congress by a 45-40 margin. That’s almost a complete reversal from last month, but the poll also shows a dangerous trend – only one-third would re-elect their own Congressmember. Far from just Teabaggers on the right who are waging a Stalinist purge of Republicans, there is disenchantment on the left that explains the malaise. And so far, the Democratic leadership and Obama White House are refusing to recognize it.

If Blanche Lincoln and Arlen Specter survive the Democratic primary, it will only get worse. There is no guarantee Specter or Lincoln would beat their Republican challengers in November – in fact, odds are against it. In Arkansas, Republican John Boozeman beats Lincoln by 14 points. In Pennsylvania, Specter quit the GOP because right-winger Pat Toomey would beat him in the primary. If they face each other in the general, Specter loses byeight points.

Does this mean their progressive challengers – Bill Halter in Arkansas, and Joe Sestak in Pennyslvania – would win? Not necessarily, but the odds are much greater. Match-up polls show both Democrats doing better against the Republican in November, but a more important metric is the “favorable/unfavorable” numbers. As incumbents, Lincoln and Specter have high name-recognition – and voters don’t like them. You can’t convince someone who’s already made up their mind to change it. With Halter and Sestak, the outcome is more fluid – because voters will be open to persuasion come November.

Democratic elites always lecture progressive activists about “electability” – how we must temper our idealism and support for liberal candidates for the “greater good” of defeating Republicans. And yet, Organizing for America – the President’s “field team” that helped him defeat Hillary Clinton and John McCain – is urging supporters to help Lincoln and Specter win the primary. While I’m sure many of us would support Lincoln and Specter (albeit grudgingly) if they win the primary, to do so now is sick and counterproductive.

Let’s review things for a minute. As a moderate Republican, Arlen Specter co-sponsored the Employee Free Choice Act in 2007 – but balked in 2009 because of pressure from the right-wing of his party. After becoming a Democrat in April 2009, he nevertheless remained opposed to EFCA and did not repudiate his prior support for a flat tax when I asked him directly. He’s been a decent Democratic vote over the past year, but only after Sestak opted to challenge him.

Blanche Lincoln’s record is even worse. As the White House pushed for health care reform, she vowed to filibuster any bill that included a “public option” – even when her Arkansas constituents supported it. In other words, she was entering in cahoots with Mitch McConnell and the Senate Republicans to block any vote on President Obama’s highest legislative priority – one he took so seriously that everything else had to wait. If Senate Majority Leader Harry Reid had a spine, this would have been treated as an act of war.

Senators rarely lose re-election – not to mention a primary in their own party – which is why it’s so hard to hold them accountable with a serious candidate. When Joe Lieberman lost in 2006, it was the first time that a Democratic Senator failed to get re-nominated in fourteen years. The fact that two incumbents now stand to get primaried in the same year is remarkable, and should be a serious “wake-up call” to the Democratic Party leaders.

But the leadership is circling the wagons – because the Senate is a “club” (often known as the world’s most exclusive club), and incumbents are terrified that a primary challenge to Lincoln and Specter could mean they’re next. San Francisco readers will recall how the State Senate rallied around Carole Migden (despite her liabilities as an incumbent), when Mark Leno ran against her in 2008. What we see right now at the national level is not all that different.

Like we’ve seen before, the task for progressives now is to save the Democratic Party from itself. We will not see the glaring “enthusiasm gap” between Democrats and Republicans shrink if Blanche Lincoln and Arlen Specter win the primary. They will stand to lose to a cadre of right-wing challengers in November, which will only embolden the Sarah Palin crowd to bring back the Bush Administration. That’s why it’s so crucial to help Halter and Sestak.

Fortunately, you don’t have to be in Arkansas or Pennsylvania to help out. MoveOn can help you call its Arkansas members, and recruit them to volunteer for Bill Halter. Joe Sestak’s campaign website enables you to make virtual calls to Pennsylvania. It is these tools that elected Barack Obama, and now we’re using them to rescue his legacy.

Of course, everyone knows that Joe Lieberman was a sore loser after Ned Lamont won the primary, stayed in the race as an independent and – with active support from Karl Rove – won re-election. But the same won’t happen this time. In both Arkansas and Pennsylvania, the deadlines to file as an independent candidate have already lapsed.