Much of this debate focuses on the constitutionality or morality of the appointment decision, arguments that I argue are without merit. Instead, the likely ideology of the Obama Supreme Court nominee turns on the incentive structure of sitting Republican Senators and that of President Obama. I show that in the case of a political climate where the Republican presidential nominee has a 50% chance of victory in the 2016 elections, Republicans will have an overwhelming incentive to refuse to confirm either a moderate progressive or a strong progressive Obama nominee. Knowing that, Obama will nominate a strong progressive because of ideological affinity and the potential for a higher Democratic turnout. The Republicans will then refuse to confirm that strong progressive. In the scenario where the Republican presidential candidate has a substantially lower than 50% chance of winning the election, Republicans will prefer to accept a moderate progressive nominee from Obama than to get a strong progressive nominee from a President Clinton or Sanders. Unfortunately for the Republicans, Obama will stand to gain substantially more from nominating a strong progressive and having him/her blocked than from appointing a moderate progressive who would get confirmed. The end result is the same: Obama nominates a strong progressive who gets blocked by the Republican-controlled Senate.
Would President Obama be violating an unwritten pact by appointing a new Supreme Court justice in the last year of his presidency?
Once some Republicans determined that they did not want another Obama nominee on the Supreme Court, they started looking for something to legitimize their position. Marco Rubio, himself a sitting Senator, argued that no Supreme Court justice was nominated by a "lame duck" president, a claim that was quickly debunked thanks to Justice Kennedy's appointment to the bench in 1988.
Others have latched on to to the "Thurmond Rule", a vague and informal "rule" adopted by the late Senator Thurmond that argued against allowing a president to make lifetime appointments in the last few months - usually up to 6 - of their presidency. The two major problems with the invocation of this "rule" is that 1) it has no legal or constitutional power, and 2) President Obama still has 11 months left in office.
Does the Senate have a constitutional obligation to seriously consider a nominee during Obama's last year in office?
Some on the political left have argued that the Senate has an obligation to give a fair hearing to any Obama nominee before 2017. However, as the Cato Institute aptly points out, "The Senate’s obligation is to do what the Senate wants, and only what the Senate wants." The relevant clause of the Constitution is Article II, Section 2, which simply states that the president "shall nominate, and by and with the advice and consent of the Senate, shall appoint ambassadors, other public ministers and consuls, judges of the Supreme Court." There is no constitutional obligation for the Senate to seriously consider any presidential nominee, a fact that has not been overlooked by the Senate in the past, most notably in the nomination of Robert Bork.
1. Will the Republican Party be punished in general elections for being obstructionist?
Republican senators, who hold an effective veto over the appointment of any Supreme Court justice, will have to respond to three separate sets of incentives. The first has to do with the strength of the Republican Party as a whole, which affects electoral success in general elections. One argument relating to the Supreme Court vacancy is that Republicans will be punished by the voters for being obstructionist. To put it simply, that is wishful thinking by Democrats. Despite attempting to block President Obama at every turn, the Senate has seen its Republican membership expand from 49 to 53 between 2008 and 2014. The House, the more partisan of the two Congressional bodies, has seen its Republican membership skyrocket from 178 in 2008 to 247 in 2014.
Perhaps there is something about the "objective" and "non-partisan" Supreme Court that will convince voters to punish anyone blocking its work? The following Gallup Poll should disabuse anyone of that notion. Due to the recent rulings on Obamacare and gay marriage, the Supreme Court is no longer viewed as standing above politics. Only a quarter of Republicans approve of the work of the Court. The same is true of 42% of independents, one of the lowest approval ratings from that group since 2001. Neither group is likely to turn against the Republicans for opposing an institution they no longer approve of. Democratic voters will be doubly upset by Republican obstructionism in this area. However, given the record party polarization we are witnessing, it is highly unlikely that many of those voters would consider voting Republican anyway.
2. Will individual Republican Senators be punished in primaries for being obstructionist?
The answer to this question is a strong no. Not only will Republican voters not punish their senators from blocking an Obama Supreme Court nominee, they are likely to punish any Republican senator who does anything else. Republican presidential candidate Chris Christie was repeatedly attacked for backing the nomination of Sonia Sotomayor. While it is too late for primary challenges in the 2016 election, any senator up for reelection in 2018 and beyond would be nearly guaranteed a challenge from the right if they support Obama's nominee to replace Justice Scalia. That is a risk that Republican senators have no need to take considering how little they stand to benefit politically from not being obstructionist.
3. What would produce the most conservative Supreme Court nominee?
This is the most interesting question facing Republican Senators. The key variable in this decision is the likelihood of a Republican becoming the next president. The value of this variable affects the payoffs of both Republican senators and President Obama. To keep things simple, I will examine two scenarios: one where the chance of Republican victory is 50% and one where it is substantially under 50%. In each case, President Obama has to decide whether to nominate a moderate progressive or a strong progressive, and Republican senators have to decide whether to accept or reject that nomination. If they reject, the next president gets to make the nomination in 2017.
The following is the payoff structure. Out of a possible score of 10, Republicans would rank a conservative justice a 10, a strongly progressive one a 0, and a moderately progressive one as less than 5 (a moderate progressive is still more likely to give the progressive justices a majority). I will make it 3 for simplicity’s sake, but the actual number does not matter. With a 50% probability of victory, Republicans can expect a mean payoff of 5 (50% chance of getting a 0 and 50% chance of getting a 10). Obama’s payoffs are mostly the reverse of the Republican ones. He would give a 10 to a strong progressive, a 7 to a moderate progressive, and a 0 to a conservative. The one twist I will include is that Obama gets an extra point for nominating a strong progressive, whether it is because he gains personally by nominating someone closer to his own beliefs or because such a nomination would boost Democratic turnout, thereby helping the Democratic Party get seats in all political races in 2016.
In the first scenario, Republicans believe there is a 50/50 chance of a Republican winning the presidency in 2016. Obama decides between nominating a moderate progressive and a strong one. If he picks a moderate progressive, Republicans can either accept, which will give them a payoff of 3 (the value they attach to having a moderate progressive join the Supreme Court) or they can reject, which gets them a payoff of 5 (the mean between a conservative in the event of a Republican victory and a strong progressive in the event of a Democratic one). Obama’s payoffs are the mirror image of the Republican ones: 7 if Republicans accept, 5 if they reject.
If Obama decides on a strong progressive, Republicans will gain a payoff of 0 if they accept (the value they attach to a strong progressive getting a seat on the Supreme Court) and 5 if they reject (same logic as before). Obama’s payoffs are 10 if Republicans accept (we get a strong progressive justice) or 6 (5 for the mean payoff plus 1 for choosing someone ideologically similar and potentially boosting Democratic turnout). The best move for Republicans in either case is to reject: 5 > 3 and 5 > 0. Knowing those payoffs, Obama will opt for a strong progressive, because he prefers 6 as the ultimate outcome (in the strong progressive case) over 5 (in the moderate case). Thus we end up with a strong progressive that Republicans reject, with the next president filling the empty seat on the Supreme Court. The entire payoff structure can be seen in Figure 1.
If Obama decides to nominate a strong progressive, Republicans can obtain a payoff of 0 if they accept (same logic as before) and 2.5 if they reject (again, assuming a 75% chance of getting a 0 and 25% chance of getting a 10). Faced with this choice, Republicans would prefer to have the voters decide instead of accepting the nomination.
There is a hitch for Republicans in this scenario, however, that being Obama’s payoffs. If Obama nominates a moderate progressive, he is likely to end up with a payoff of 7 (the reverse of the Republican payoff given that Republicans would accept this nomination). If he nominates a strong progressive, he would instead get a payoff of 8.5 (7.5 being the reverse of the Republican payoff plus an extra point for nominating a fellow strong progressive). In fact, even without the boost from the extra point, Obama will now prefer to nominate a strong progressive knowing that Republicans will block him/her, and the next president would be in a positive to appoint the same kind of a strong progressive. Despite Republicans being willing to accept a moderate progressive, they will not get that choice. The outcome is Obama nominates a strong progressive and Republicans refuse to confirm that nomination. To put it another way, within the confines of this game and the assumptions used to create it, Obama will always nominate a strong progressive and Republicans will always block them. The math behind the logic can be seen in Figure 2.