In the immediate wake of Justice Scalia's death, Senate Majority Leader Mitch McConnell very quickly announced that President Obama should not name Scalia's successor. A great deal of attention has been paid (including by the Onion) to the political posturing that has taken place in the hours and days since.

Understandably, much of it focuses on what kind of nominee might actually be nominated and whether such a nominee would actually be confirmed. We're going to take a different tack and consider why McConnell so quickly tried to preempt a nominee in the first place.

There's no harm in looking, right?

Formally, it is very easy for McConnell and his Republican colleagues to ensure that no Obama nominee would be confirmed (though the Democrats could make life difficult). Given this, then standard "gatekeeping'' logic (see here) implies that the GOP can only gain from at least seeing whom Obama would nominate: If Obama nominates an unacceptable nominee, the GOP senators can simply say no to whomever Obama nominates.

Furthermore, withstanding the pressure to vote on an Obama nominee could help GOP incumbents signal their commitment to the conservative principles, such as gun rights, that Scalia stood for on the Court. This logic is laid out by one of us in "Signaling Through Obstruction" (ungated version).

The fear of being seen as extreme

However, from a strategic standpoint, McConnell might fear that 14 or more of his colleagues would not be willing to obstruct a moderate and well-qualified nominee. In fact, some senators might actually be willing to vote for a relatively liberal nominee because they fear being perceived as too conservative by moderate voters. This logic lies at the heart of the reaction described by Tim Groseclose and Nolan McCarty.

The possibility of incumbents fearing the blame game is unusually important for McConnell this year because the GOP has 24 Senate incumbents up for reelection this year, and of the 12 competitive Senate races this year, 10 are for seats currently held by Republicans.

Naturally, most of those competitive seats are in states where the electorate is relatively more moderate — places like Illinois (Mark Kirk), Missouri (Roy Blunt), North Carolina (Richard Burr), New Hampshire (Kelly Ayotte), and Ohio (Rob Portman). Such incumbents might worry that obstruction would be too costly in terms of alienating independent voters in the general election. Indeed, see Kirk's op-ed from Monday, in which he wrote:

I recognize the right of the president, be it Republican or Democrat, to place before the Senate a nominee for the Supreme Court and I fully expect and look forward to President Barack Obama advancing a nominee for the Senate to consider.

The devil's in the details

Putting the "Signaling Through Obstruction" and "Blame Game" logics together creates a rich set of scenarios for McConnell, who is undoubtedly uncertain not only about how the electoral environments facing his 24 colleagues will unfold, but also about how these colleagues will behave as the election progresses. Accordingly, he may have a strong incentive to avoid forcing his colleagues to go "on the record" with either a vote on a Supreme Court nominee, or with being seen as complicit in obstructing one, particularly one who will likely be widely perceived as extremely qualified and politically moderate.

After all, if there is no nominee to vote for or obstruct, voters cannot infer much, if anything, about their incumbents' stances from their actions. As has been well documented by political science research (see here and here for examples), senators are sensitive to opinion among their political base when voting on Supreme Court nominees. At the same time, well-qualified, moderate nominees tend to be broadly politically popular.

In other words, the problem for McConnell is that if President Obama selects a well-qualified, politically moderate nominee, Republicans will have to decide whether to go on the record voting against the nominee, revealing themselves to be ideological extremists, or to support a political moderate, nominated by President Obama, potentially upsetting their political bases. In the context of a competitive election, the choice is then between the base and independents, both of which are necessary to win reelection in closely divided states.

In line with all of this, and as one of us has pointed out in another post, there may be a strong interest among Democrats in keeping the nomination debate going as part of the election, whereas Republicans might have a distinct interest in ending the discussion (or at least hiding it from public discussion until after the election).

Weighing 34 Senate races against one presidential election

Many have speculated that McConnell's reluctance is due to his hope that a future Republican president might nominate Justice Scalia's replacement. However, our logic suggests a different rationale. Given President Obama's relatively constrained political capital and the GOP's control of the Senate, this seems like a good opportunity for the Republicans to press Obama for a moderate nominee. However, that might be exactly what McConnell fears!

McConnell's desire to preempt any Obama nominee is motivated by the fear that, when confronted by a nominee, his GOP colleagues will confront a Catch-22 in which, regardless of what they say or do, the GOP's prospects for maintaining control of the Senate in 2017 will be worsened. Scalia's passing rocked the political scene, and left Mitch McConnell in a very hard place indeed.