Conventional wisdom states that Republicans have every political reason to block anyone President Obama nominates for the Supreme Court.
Any Republican who voted for an Obama nominee could face a primary challenge. The people who care most about judicial battles are ideological base voters, so swing voters in a general election wouldn't blame one party over the other. And if a Republican wins the presidency, then Senate Republicans would confirm a conservative, while if a Democrat wins, the person's nominee would be no different from an Obama nominee. Nothing lost by holding out.
But there are reasons to question all of these assumptions.
First, the immediate electoral risk for Republicans is in the general election, not the primary.
There are 21 incumbent Senate Republicans up for re-election in 2016. (Three other Republican incumbents are retiring from the Senate.) Six of them, five of which are in "blue" states, are rated as "toss-up" or "lean Republican" (as opposed to "likely" or "solid" Republican) by the Cook Political Report.
These six - Sens. Kelly Ayotte (N.H.), Ron Johnson (Wis.), Rob Portman (Ohio), Mark Kirk (Ill.), Pat Toomey (Pa.), Richard Burr (N.C.) - were all elected to their first terms in the Tea Party-infused 2010 midterm. This time, they will be running in a presidential year in which Democratic turnout will be higher.
Kirk, Portman, Toomey and Burr have primary challengers. But none have gained traction yet, and the primaries for most are soon - all in March except for Toomey's in late April. Any vote on a court nominee would likely come after that.
(The one probably worried the most about a primary challenge is New Hampshire's Ayotte; her primary is not until September, the filing deadline is June and Trump's presidential primary win showed an unruly anti-establishment GOP electorate.)
For the other 15 "safe" Republicans up for re-election, several face nominal primary challenges, 10 of them in June or later. These folks won't want to take any unnecessary political risks.
That leaves 30 Republicans who don't face any immediate electoral pressures.
They may have a reason to worry about future primaries; political scientist Dave Hopkins noted that longtime Sen. Dick Lugar was ousted in the 2012 primary after voting for Obama nominees in 2009 and 2010. But those were votes for nominees that were considered to be "liberal" picks. The political dynamic around a pick widely deemed to be a centrist would be an entirely different ballgame.
That brings us to the second assumption: only base voters care about judges.
It's an understandable assumption. It has been true when we've had Senate scrums over lower court judges. It has been true when voices on one side of the spectrum futilely try to rally opposition to a judge on the other side. (Contemporaneous polls showed little public interest in the epic 1991 Clarence Thomas and 1987 Robert Bork battles, not to mention the less-remembered 2005 conservative kneecapping of Harriet Miers.)
But none of those episodes happened in the middle of a presidential election.
In fact, SCOTUSBlog checked the record going to back to 1900, and found no instance of a Supreme Court seat left vacant on Election Day. If Republicans refuse to approve anybody by November, we will be in a truly unprecedented situation.
The public won't tune out of the judicial battle because a presidential election season is the one time when most people tune in. And no matter who Obama picks, barring a poor vet and unexpected scandal, Republicans will be on the losing side of the argument.
Obama is highly unlikely to pick a left-wing version of a Bork. He would either pick someone in the "mainstream liberal" mold of Sonia Sotomayor or Elana Kagan, or he would offer a compromise choice, a centrist swing vote - perhaps negotiated with some Senate Republicans - putting the Supreme Court in perfect ideological balance.
Either direction squeezes obstructionist Republicans.
Republicans would have a relatively easier time resisting a mainstream liberal, or more accurately, it would be a bigger risk for individual Republicans to cross the aisle and vote for a mainstream liberal. That could be used against a Republican in a primary this year or beyond.
Nevertheless, a general electorate majority would embrace a mainstream liberal since he or she would uphold rights that are widely embraced, including abortion rights under Roe v. Wade and equal rights for gay people. Putting those hot-button social issues on the line for Election Day is an clear-cut loser for Republicans. Not only would Republicans be more likely to lose the presidency, they would also be more likely to lose the Senate.
Naming an undisputed non-ideological judge would put Republicans in an even worse political bind. A nominee showered with praise from the legal establishment as an eminently qualified straight-shooter would isolate Republicans as hostages to ideological extremists. They would not be able to claim that they were protecting the court from a dramatic ideological shift; they would be exposed as holding out for their own ideological comrade at the expense of good governance.
And that brings us to the final assumption: that Republicans lose nothing by holding out. On the contrary, they could lose everything.
As it stands, Republicans have the ability to bargain with Obama and win that compromise pick, ticking the court a half-step leftward into exact ideological balance.
By refusing to bargain, Republicans weaken their general election prospects for both the White House and Senate. If Democrats take both, they could install a young liberal - as well as replace older liberals Ruth Bader Ginsberg and Stephen Breyer - and create a five-person Court majority that would rule for a generation.
Seeing the madness that is the Republican presidential primary, one could see why the Republican Party's first instinct is to reflexively obstruct. But after making a cold calculation, clear-headed Republicans will see that the logical move is to make a deal.
The only question remains: How many clear-headed Republicans are left in the Senate?
