This is a question Senate Majority Leader Mitch McConnell will answer.
But The Sensible Conservative offers unsolicited advice: BEFORE.
The risk in the Senate voting before the Nov. 3 election according to some Republican observers is that some vulnerable incumbent GOP Senators such as Susan Collins of Maine and Cory Gardner of Colorado will lose their re-election bids if they vote for the nominee. And they may be right. GOP control of the Senate majority may be lost as a result.
On the other hand, taking the vote after the election – which there is a distinct possibility that Republicans will lose both the White House and control of the Senate anyway - carries a risk that a lame duck Senate may refuse to confirm President Trump’s choice. Defeated Republicans may believe – out of a sense of admirable conscientiousness – that they have lost also their moral right to oppose the will of their state’s voters. Further, with President Trump’s ouster, other GOP Senators may be tempted to oppose his nominee because they perceive no harmful consequences to their careers by doing so.
A vote before the election in the current political climate is highly likely to succeed and another conservative will be added to the Court. But the chances of losing the Senate may increase.
A vote after may place the prospects for a new conservative Justice in doubt, however.
What to do?
Loss of the senate will be most undesirable, of course. But there will be another election in two years. The opportunity to put another Conservative on the Supreme Court may not come soon again.
Given the choice, I strongly believe long term solid control of our highest court is more important than continuing domination of the U.S. Senate.