Sullivan's political affiliation is not clear. He was first appointed to the bench by Reagan. He was subsequently elevated by both HW Bush and then by Clinton.
My guess is he's more interested in the law than in political ideology. Which, probably makes him sadly uncommon in today's judiciary.
Judge Sullivan’s initial appointment to the D.C. Superior Court by Reagan doesn’t mean anything politically. We’d like to think judicial appointments are apolitical but they usually aren’t. What is?
In the case of the DC Superior Court, the local bar proposes to the current Administration its nominees from which the POTUS selects. So, much of the politicking that goes on is within the local bar, then the Administration chooses which of the nominees gets the appointment. It is thru this process that the DC court ends up with either truly good judges or the incompetent partner a firm is trying to get rid of .. there is little in between.
I know several attorneys of different political persuasions who’ve appeared before Sullivan both in the DC Superior Court and at the US District Court for DC, and he really is well regarded.