Has Obama Been Eating the "Blue Dog" Democrats?

According to the progressive argument, the mainstream media, and pseudo-conservatives such as David Frum and Jennifer Rubin,  the Tea Party groups have radicalized the GOP moving them to extreme right wing positions.

While everyone is concentrating on us tyrannical conservatives they have missed the real story.  One by one members of the "Blue Dog" Democratic caucus have been disappearing from Congress

According to Fox..the Democratic party is now ruled by unions and others in the far left:

In Tuesday’s Pennsylvania Primary, two members of the Blue Dog Coalition, the Clinton-era House caucus of moderate Democrats came up short against more liberal opponents.

Rep Tim Holden, who has represented a district stretching east from Harrisburg for a decade, lost to a personal injury attorney, Matt Cartwright.

Rep. Jason Altmire, who snatched a Republican-held seat in suburban Pittsburgh during the Democratic wave election of 2006, lost in a member-on-member primary to Rep. Mark Critz, the labor-backed successor to the late Rep. John Murtha.

The Obama era has been murder on the Blue Dogs. There were 54 members in 2009 but only 26 in 2011.

Obama’s health law is one of the main culprits. After the president made promises about fiscal constraints, most of the members signed on to his health law. Those votes proved fatal to the careers of several members from red-leaning districts who either retired in the face of impossible odds or were beaten.

Altmire and Holden survived by voting against the health law and survived the Republican wave of 2010. But, they paid the price for disloyalty last night as Democrats picked backers of the Obama law over opponents. Labor groups started their campaign in 2010 with anti-incumbent efforts against Democrats in Arkansas, Pennsylvania and elsewhere.

To get a sense of the power unions hold in the new Democratic Party, not one endangered Senate Democrat could be enticed on Tuesday to vote for a Republican-backed measure that would have blocked a move by the National Labor Relations Board creating snap elections. A vote for that bill could have been a big help to red-state Democrats, but none would buck the unions on the issue.

Of course that's what Fox News claims. If these "blue dogs" were disappearing because the Democratic party has become more radical, why haven't we heard about the radicalization from the main stream media. Could there be a more epicurean-oriented reason for the disappearance?