Updated

“Redistricting and a broken, polarized Congress have made it tough to be a moderate in Congress.”

-- Rep. Mike Ross, D-Ark., the head of the Blue Dog Democrats in the House, in a statement lamenting the defeat of two members of the group, Rep. Tim Holden and Rep. Jason Altmire, in Tuesday’s Pennsylvania primary.

The Democratic argument for 2012 is that the Republican Party and its presidential nominee, Mitt Romney, have been radicalized by a “reign of terror” from conservatives and libertarian-minded members of the Tea Party movement.

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Maybe so. Of course, the very fact that moderate Romney managed to capture the nomination in surprisingly fast fashion does belie the Obama campaign’s argument a bit. The Romney of 2012 is pretty much the same as the Romney of 2008. Different, especially on social issues, from the Romney of 2004 and 1994, but we saw no major shifts since his first presidential run.

Democrats, though, are clearly facing a terrifying reign of their own as liberal activists and unions keep hounding moderate members out of office.

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.

Redistricting is in large part to blame for both defeats. Pennsylvania lost two seats in the 2010 reapportionment and the Republican-controlled state legislature redrew the map to make it harder for moderate Democrats. Holden saw his district shift north and west into more liberal, more pro-union counties to the northeast. And the mash up of Altmire and Critz’s districts meant one Democrat was sure to lose.

But there’s more at work here than just redrawn district lines. Democrats have become less tolerant of the moderates in their midst, and the growing influence of unions, especially government worker unions, is a big part of the reason.

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.

Three consecutive wave elections have left Americans with the most conservative House since the 1930s, the most liberal president since Lyndon Johnson and the Senate at a standstill. With so little middle ground, voters will face a stark and decisive moment this fall.

The idea of a Clintonian “Third Way” for Democrats is a distant memory and with government unions playing an increasingly important role for the party, leftward seems to be the only available direction.

The Day in Quotes

“That’s basically a tax hike for more than 7 million students across America -- more than 160,000 students here in North Carolina alone.”

-- President Obama talking about the July 1 expiry of a $6-billion-a-year federal student loan subsidy program for lower-income college students during a campaign rally at the University of North Carolina at Chapel Hill.

“To all of the thousands of good and decent Americans I’ve met who want nothing more than a better chance, a fighting chance. To all of you, I have a simple message: Hold on a little longer.  A better America begins tonight.”

-- Presumptive Republican nominee Mitt Romney at a campaign rally in Manchester N.H. amid a Tuesday-night sweep of five Republican primaries – New York, Pennsylvania, Connecticut, Rhode Island and Delaware.

“I know, but I decided the results were clear enough.”

-- Newt Gingrich amid a quintet of wide primary losses on Tuesday responding to a reporter who reminded the former House speaker that he had promised to take questions from the press.

“Everybody here and in this audience knows, it is determined through global economics, no one has the ability, not even Harry Potter, okay?”

-- Interior Secretary Ken Salazar talking to reporters about the criticism of the Obama administration’s energy policies.

“But personally, I think Keystone is a program that we’re not going, that I am not going to help in any way I can. The president feels that way. I do, too.”

-- Senate Majority Leader Harry Reid telling reporters that he would block a House-passed transportation bill that includes an authorization for the Canadian oil pipeline denied by the Obama administration.

“We are busy in Washington with a corrupt government, with a government that I said, perhaps, because of the money, the amount of TARP and stimulus funds, was going to be the most corrupt government history and it is proving to be just exactly that.”

-- Rep. Darrell Issa, R-Calif., chairman of the House Oversight Committee, talking to Bloomberg News.

“[Iran’s nuclear centrifuges are] spinning as we speak. So if the sanctions are going to work they better work soon."

-- Israeli Prime Minister Benjamin Netanyahu in an interview with the Cable News Network.

“If these zealots have their way, our hard-won sexual liberation — women’s rights, reproductive rights and rights to privacy — lie in peril.”

-- Former Playboy magazine Publisher Hugh Hefner in an editorial in the magazine attacking presumptive Republican nominee Mitt Romney and others in his party of “a war on sex.”

Chris Stirewalt is digital politics editor for Fox News, and his POWER PLAY column appears Monday-Friday on FoxNews.com.