At National Journal, Josh Kraushaar suggests that what had been a sublimated divide between DLC-style moderates on the right and labor-liberals on the left has grown sharper during the Obama years. For obvious reasons, the Bush presidency sharply reduced intraparty tensions. For a number of reasons, Democrats who had been champions of economic rigor and a more hawkish foreign policy moved left while Democrats who favored a more active regulatory interventions, industrial policy, and a more steeply progressive tax code felt vindicated in the wake of the financial crisis. Kraushaar describes the growing tensions:

Conversations with liberal activists and labor officials reveal an unmistakable hostility toward the pro-business, free-trade, free-market philosophy that was in vogue during the second half of the Clinton administration. Former White House Chief of Staff William Daley, who tried to steer the Obama administration in a more centrist direction, is the subject of particular derision. Discussion of entitlement reforms, at the heart of the GOP governing agenda, is a nonstarter. The fiscally conservative Blue Dog Democrats are now nearly extinct on Capitol Hill.
Moderate Democratic groups and officials, meanwhile, privately fret about the party’s leftward drift and the Obama campaign’s embrace of an aggressively populist message. They’re disappointed that the administration didn’t take the lead advancing the Simpson-Bowles deficit-reduction proposal, they wish the administration’s focus was on growth over fairness, and they are frustrated with the persistent congressional gridlock. Third Way, the centrist Democratic think tank, has been generating analyses underscoring the need for Democrats to appeal to middle-of-the-road voters, to no avail.

He offers this context to help explain the firestorm set off by Cory Booker’s apparent defense of Bain Capital against some of President Obama’s sharp-elbowed attacks, a defense that Booker has been careful to walk back.

Booker is a leading figure in the centrist faction, and he didn’t hide that fact when he called out the Obama campaign attacks against Romney’s private-equity work. He first made a name for himself by challenging the party’s establishment in the 2002 Newark mayoral race, taking on the cronyism that was endemic in city government. After being elected in 2006 on his second try, he’s worked closely with the business community to revitalize Newark. He’s developed an unlikely odd-couple relationship with Republican Gov. Chris Christie, and the two have rallied behind education reform, taking on the teachers’ unions in the process.
The Booker governing model, premised on bipartisanship and taking on ideological party factions, runs contrary in many ways to Obama’s record. It’s why Booker’s call for Obama to elevate the rhetoric drove Chicago batty: It was a stinging reminder that the candidate’s promise of a post-partisan approach in 2008 had given way to the reality of governing in a polarized Washington and the necessity of running a highly negative campaign against Romney.

One central problem for Team Obama, as Kraushaar explains, is that Booker’s brand of politics resonates with the affluent, college-educated voters who constitute an increasingly crucial part of the Democratic coalition. This is a group that Republicans need to peel off, yet the GOP’s dominant cultural style has proven repellent to these voters for much of the post-Clinton era.

This is why it is so important that Republicans embrace Clinton Democrats who’ve grown increasingly uncomfortable with their party. The problem, however, is that a more ideologically-unified Republican Party is fiercely resistant to compromise on core cultural issues. We’ve seen the GOP grow somewhat more tolerant of disagreement on same-sex marriage and gay rights more broadly. There remain considerable hurdles for Republicans who don’t embrace the party’s consensus on abortion rights, partly due to the greater intensity of anti-abortion voters and the fact that the number of voters who identify as broadly pro-life is quite high — indeed, in some surveys it is higher than the number who identify as pro-life. One unfortunate consequence of this phenomenon is that talented politicians like Nevada Gov. Brian Sandoval face a political ceiling, as do Republicans based in socially liberal regions with large numbers of religiously unaffiliated voters like the Pacific Northwest and New England. It is hard to imagine the charismatic Sen. Scott Brown ever serving on a national ticket, for example. A core Republican strength — the fact that there are a large number of self-identified conservatives in the electorate — can at times be a weakness, as Democrats are more accustomed to the idea that they must be a coalition party that unites liberals and moderates.