Senator Blanche Lincoln (D-Arkansas) is in trouble. Her approval ratings are weak, and Republicans have targeted her for defeat in November. But because she also filibustered health care reform and killed the public option, Democrats don’t like her either. She now faces a primary challenge from Lieutenant Governor Bill Halter. The White House has endorsed Lincoln because she’s the incumbent, and last week did a radio ad for her. But in the ad, Obama says she “took on big insurance companies” to pass health care. Of course, nothing can be further from the truth. Democrats have an “enthusiasm gap” with Republicans, and a low turnout could spell disaster in November. It’s natural for progressives to target conservative Democrats like Lincoln who are to blame, fielding primary challenges like they did to Joe Lieberman. But how the Party leadership berates, belittle and insults these efforts will only make it worse – while a clear anti-incumbent mood is sweeping the nation that threatens to doom Blanche Lincoln anyway.

Arkansas is just the most extreme example this year of Obama standing up for doomed incumbents who have frustrated the progressive agenda that got him elected in the first place. Meanwhile, liberal activists are simply doing what they know is right – hold the Democrats accountable by running targeted primary challenges when it is appropriate.

Make no mistake about it – Blanche Lincoln is a major reason why it took so long to pass health care reform, and why the bill was stripped down to what it finally became. Last November, she openly promised on the Senate floor that she would filibuster health care reform – unless the public option was dumped.

She can’t make the excuse that she was from a conservative state like Arkansas – 55% of her constituents supported it. Because the insurance companies hated the public option so much, Blanche was willing to actively collude with Mitch McConnell and the Senate Republicans to block health care from even coming to a vote – let alone pass.

Obama didn’t go so far as to claim that Lincoln supported the public option (even she brags in her ads about killing it.) He was careful to say she “took on” the big insurance companies by making it illegal to deny pre-existing conditions. But even that’s a lie. Lincoln was one of only three Senate Democrats to vote against the final health care bill (even Joe Lieberman was a team player, and voted for it.)

The Arkansas Democratic primary is May 18th, and progressives have mobilized around Bill Halter to defeat Blanche Lincoln. With a third candidate running, it is likely to go to a run-off on June 8th. But even if Lincoln wins the nomination, she’s more likely to lose in November than Halter – who consistently polls better than her in general election match-ups. So in an election year where his agenda is at stake, Obama is lying to defend a very unpopular Senator – and if successful, chances are Republicans will win the seat in November.

There’s no rational political strategy behind this – except to defend the chumminess of the U.S. Senate. It’s the world’s most exclusive club, and members look out for each other. Take Pennsylvania’s Arlen Specter – another longtime Senator who’s in trouble. Arlen was a Republican, but he switched parties last year when it became clear he would not survive a GOP primary challenge. He even said he was switching parties to save his job.

Now, despite having a real Democrat challenge him in the primaries (Congressman Joe Sestak), the White House is behind him – and so are the Party bosses. Sestak has been picking up support, and could very well win the upcoming primary – so now they’re in damage control mode. Pennsylvania Democratic Chair T.J. Rooney said last week he was “worried” Sestak winning the nomination would be “cataclysmic” to the Party’s chances in November. Never mind they could be screwed either way – as Specter currently lags behind the Republican.

The problem with this “Defend the Club” strategy is that voters – on both the left and the right – are angry this year, and we’re likely to see many incumbents lose. If Democrats and the Obama White House want a progressive legacy to survive for next year, they are foolish to be propping up weak Democratic Senators who have betrayed the Party – and are getting well-deserved challenges from the Left. Bill Halter and Joe Sestak would run in November without the baggage of being part of the problem in Washington DC.

This is not the first time that Obama has slavishly defended Senate incumbents who are facing primary challenges – but he didn’t use to be so tone deaf about it.

In 2006, he endorsed Joe Lieberman – when the Connecticut Senator was facing a primary challenge. At a State Party dinner, Obama said: “I know that some in the party have differences with Joe. It's the elephant in the room. And Joe and I don’t agree on everything. But what I know is, Joe Lieberman’s a man with a good heart, with a keen intellect, who cares about the working families of America.”

Notice that he didn’t pretend that Lieberman was against the Iraq War – which is what had fueled Democrat Ned Lamont to take him out in the primaries. Obama gave other reasons in defense of the Senator. And that’s the difference between now and then – when defending Blanche Lincoln, the President has to lie about her health care record.