Interesting comments. I guess it is also like confirmation bias in a way.
Yes, confirmation bias feeds into it. The Kahneman book talks about all that stuff and shows how they all feed into one another and create different biases.
Since my partisan values Republican policy positions then me being on the democratic side as of late supporting impeachment seems to be an anomaly with respect th this theory. Correct?
No, I would disagree. The Halo Effect is a reaction to the individual.
If you have values that align with the Republican party, then candidates with traditional Republican party membership may give you greater confidence because you know what to expect from them; especially when compared to Democrats. But
within the party, you may intensely like or dislike particular figures. Witness how the Democrats are sorting out their feelings toward the primary candidates as they try to figure out whom they'll back in 2020 based on limited exposure from a few debates and some policy papers.
Also, Trump comes from outside the Republican party and has his own separate history as a result of decades as a major public figure (a "mover-and-shaker") in NYC and New Jersey. And he was a Democrat (a "limousine liberal") most of his life. When he belatedly joined the Republican party to run in the 2016 elections, he incited both love and hate among Republican party loyalists. Take the example of the "never-Trump" faction within the Republican party, who hate Trump even more than the Democrats if that's possible. Some of them did like you and exited the party entirely rather than back Trump.
Anyway, it's important to remember that the Halo Effect is personal. That's why candidates from outside the party (third-party candidates) or from its outer "wings" have the power to realign the parties and cause big shifts in the membership and party values: They carry emotional sub-currents not traditionally aligned with the party center.
Something like that, anyway, as I see it.
Anyway, stop trying to make my post about you and your personal feelings about Trump. Like I said: I intended my post as a "meta" thing, not as a way of pointing my finger at individuals.
The theory works better on a mass basis; it's overkill for me to try to read your mind individually without even knowing you and figure out why you may or may not like this or that particular public figure.
If the theory interests you, read Kahneman's book. He's the expert on the subject, and he deals with the Halo Effect and other cognitive biases for 500 pages. Look in the back index: He makes numerous references to the Halo Effect throughout the book, besides devoting a section entirely to it. Plenty there to chew on.