It’s safe now to forget about the “red state four,” the quartet of Democrats whose defeats in conservative-leaning states last year assured the Senate GOP takeover. And the inevitable creation of the next “gang of six” (or eight, or 12, or whatever) is at least one legislative impasse in the future.  

For now, the grouping of senators deserving the most attention is the “centrist seven,” the cluster of Democrats who stand out as the likeliest to get behind aspects of the new Republican majority’s legislative program. And they may be joined once in a while by as many as five others in their party who’ve shown flashes of moderation in the recent past, yielding a universe of potential aisle-crossers who could be dubbed the “dispositive dozen” of the 114th Congress. They are the centrist Democrats most essential to Mitch McConnell in his debut as majority leader.  

Given that a united Republican front produces just 54 votes, the Kentuckian will be perpetually in the hunt for at least six Democrats necessary to overcome the legislative filibusters orchestrated by their own leadership.  

Whenever a GOP proposal gets to President Barack Obama’s desk, only to be returned with a veto message, it’s likely going to take the support of all 12 of the somewhat independent Democrats in the caucus (and maybe even one more) to override the president and push the bill toward enactment without his signature.  

It’s an extraordinarily tall order because the 10 men and two women on the roster have no past record of voting as a bloc, and they’ve done nothing to signal they would band together now into anything close to the formalized Blue Dog Coalition in the House. And, as on that side of the Capitol, the universe of Democratic centrists who might find common cause with the GOP has shrunk dramatically. Ten senators who could fairly be labeled Democratic moderates have left since the end of 2010.
At the heart of the group are four from reliably Republican states who won’t face the voters in re-election bids for three more years, each of whom already is among the most likely to go against the grain of their Democratic colleagues. That’s Joe Manchin III of West Virginia, who broke from the party mainstream on roughly one of every six roll call votes in 2014, far more than anyone else in the caucus; Heidi Heitkamp of North Dakota; Joe Donnelly of Indiana; and Jon Tester of Montana, whose centrist streak will be courted on the floor even as he takes charge of raising money and recruiting candidates from across the ideological spectrum as chairman of the Democratic Senatorial Campaign Committee this cycle.  

The others in the core group are Maine’s Angus King, an independent who caucuses with the Democrats but cultivates his reputation as an iconoclast; and Virginians Mark Warner and Tim Kaine. (The state’s purple stripes were on vivid display in November, when Warner came perilously close to losing the year’s biggest upset in part because he was portrayed as not moderating his voting record as advertised.)  

Operatives in both parties identify the senators in the current secondary circle of centrists as Michael Bennet, who will be pressed to move toward the middle ahead of his 2016 campaign for a second full term in swing-state Colorado; Thomas R. Carper of Delaware, and three others who have until 2018 before running again in potential tossup states: Bob Casey of Pennsylvania, Martin Heinrich of New Mexico and Claire McCaskill of Missouri, who announced Monday that she planned to continue her political career in the Senate rather than run for governor next year.  

McCaskill, Manchin, Heitkamp, Kaine and Warner were the five returning members of the caucus who most clearly signaled their independence from the leadership in November, when they voted against retaining Harry Reid as Democratic leader.  

McConnell has decided to waste no time in testing the possibilities and limitations of his reliance on the other side. As he seeks to show the new GOP majority is less interested in confrontational deadlock than in legislative accomplishment — along with restoring the Senate’s reputation as a somewhat deliberative place — it’s no accident the first policy legislation he’s brought to the floor has as much Democratic support as anything else the GOP wants to get done this year.  

He did not begin with trade liberalization, financing an overdue wave of public works, revamping the corporate tax code, limiting environmental regulations or narrowing the 2010 health care law’s reach — all goals the GOP and some of the moderate Republicans share. Instead, he chose legislation that would effectively order construction of the Keystone XL pipeline , designed to carry more than 800,000 barrels of crude oil a day on a 1,179-mile journey from the tar sands of Canada to the refineries along the Texas Gulf Coast.  

Nine members of the dispositive dozen voted during the lame-duck session for a bill to begin building the pipeline, and they are all expected to join the Republicans in supporting whatever Keystone-centered energy policy package the Senate assembles by the end of this month: Manchin, Warner, Donnelly, Heitkamp and Tester from the core group of seven, plus McCaskill, Carper, Casey and Bennet from the second team.  

Their support would give undeniable bipartisan credentials to the bill. But it would still mean only 63 “yes” votes, four short of what’s needed to assure a veto override. A strong showing in McConnell’s first outing, in other words, but not dispositive in the way he wants.  

Related:

Joe Manchin Open for Legislative Business


McCaskill Won’t Run for Governor


28 House Democrats Defy Obama to Vote for Keystone


What the Landrieu Adieu Says About the 2015 Senate


This Democrat Could Be the McConnell Whisperer


5 Things That Could Get Done in a Divided Government


Senate Democrats Talk Life in Minority, Plot Comeback


The 114th: CQ Roll Call’s Guide to the New Congress


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