It will be interesting to see what he tries. His normal instinct is to be confrontational and he may think selecting a minimally-qualified person that appeals to a part of his base (like he did with Sotomayor and Kagan, to appeal to Hispanics and lesbians) will fire up Democrats in the election, especially if the Republicans delay a vote. But that would remind the Republican base of the stakes involved in this election. So maybe he will go for a stealth nominee (on the surface well-qualified and not partisan, but a reliable vote for the Left once on the Court).
But Valerie may dictate to him that Kamala Harris must be the nominee.