They also make an interesting argument: by refusing to consider President Obama's nominee in order to delegate the power of appointing a new justice to the next president (whoever that may be) the Senate is violating the constitutional scheme. Although the Senate may reject a nominee for political reasons, the Senate may not refuse to act altogether in order to delegate the task of appointing a judge from a sitting president to a future president.
They point out that:
Historically, in every one of the 104 prior cases where an elected President has faced a Supreme Court vacancy and has nominated a replacement prior to the popular election of a successor, that President has been able to both nominate and appoint a replacement Justice—by and with the advice and consent of the Senate. Constitutional text, structure and history thus speak in a uniform voice.This is what we would expect. Elected Presidents who face a Supreme vacancy should be able to nominate a replacement and have the replacement considered by the Senate because that's what the constitution contemplates, even if it may take several tries.
To be sure, the Senate can and should still thoroughly vet any candidate, including Judge Garland, and scrutinize the candidate’s record and suitability for a seat on the Supreme Court. Senators also have wide latitude to vote down particular nominees, and the Senate has broad discretion to determine its procedures for evaluating nominees. However, an outright refusal to do anything at all with respect to nominees is a different matter. There is no precedent for that approach and considerations of constitutional text and structure weigh against it.What other constitutional arguments can be brought to bear? And who will take this up, and where?
I can't imagine that the justices on the Supreme Court would not be receptive to imposing some order on what is a very broken judicial nomination process if they are provided with an opportunity to interpret Article 2, Section 2 of the constitution ("President shall nominate, .... and with advice and consent of the Senate, shall appoint....") Heavens knows they've all been put through the ringer.