If I'm a conservative, I'm looking at worst case scenario.
Would I rather have a SCJ nominated by Obama, or by Bernie Sanders?
I've been critical of Obama but I don't think there would be a significant difference in the ideology of the justice they would nominate.
In the end, the pool of appointable justices is low. However, Sanders is more liberal and ballsy, and may be more willing to push the envelope.
It's clear that the strategy to hold out is a Hail Mary, because I've watched several debates, and none of the conservative nominees have a shot at a general election. A liberal justice is getting named now or 400 days from now. If I'm hedging my bets, I'm pushing for Obama to go now because he's more likely to go for a more moderate voice in an election year.
At least that's my opinion. Could be wrong.