Did Umbridge hold prejudices towards muggle-borns before the fall of the Ministry?

Question

In Order of the Phoenix, Harry speculates that Dolores Umbridge might be a Death Eater, but Sirius replies that "the world isn't split into good people and Death Eaters". I think this moral complexity is the most interesting aspect the Harry Potter series.

To that point, Umbridge does appear to employ a sliding-scale of ethics as the moral landscape of the series shifts. This gives her a fairly unique perspective on the simplified "racism is bad" theme that the series seems to have been reduced to post Book 7.

My questions is: We know from Order of the Phoenix that Umbridge had an odd aversion to so called "half-breeds" (e.g. Hagrid, centaurs, etc.), but do we ever get any indication that she is prejudiced towards muggle-borns or half-bloods (or even muggles in general) prior to the fall of the Ministry of Magic or her obtaining the locket horcrux in Deathly Hallows?

Could this be a prejudice that developed under convenient circumstances or one exacerbated by the locket horcrux? Does she ever show prejudice towards muggles in general?

Answer 1

Absolutely

Though she wasn't quite as open about it as the Death Eaters were, she definitely had some...strong opinions on the matter. There's a rather long bit of writing on Pottermore about Umbridge, and her anti-Muggle sentiment is mentioned or implied a few times (emphasis mine):

Dolores’s parents were unhappily married, and Dolores secretly despised both of them: Orford for his lack of ambition (he had never been promoted, and worked in the Department of Magical Maintenance at the Ministry of Magic), and her mother, Ellen, for her flightiness, untidiness, and Muggle lineage. [...] Dolores never saw her mother or brother again, never spoke of either of them, and henceforth pretended to all she met that she was a pure-blood.

[...]

Nasty things tended to happen to people who asked about Orford, or anything that Dolores did not like talking about, and people who wanted to remain on her good side pretended to believe her version of her ancestry.

[...]

After a glass of sweet sherry, Dolores was always prone to spout very uncharitable views, and even those who were anti-Muggle found themselves shocked by some of Dolores's suggestions, behind closed doors, of the treatment that the non-magical community deserved.

[...]

When the Ministry was taken over by the puppet Minister Pius Thicknesse, and infiltrated by the Dark Lord's followers, Dolores was in her true element at last. Correctly judged, by senior Death Eaters, to have much more in common with them than she ever had with Albus Dumbledore, she not only retained her post but was given extra authority

Although this is something of informed prejudice (that is, we're told she's prejudiced without actually seeing much evidence for it), the locket doesn't create bad feelings, it just enhances and twists what's already there, as Ron says at one point:

[I]t made me think stuff - stuff that I was thinking anyway, but it made everything worse.

^{Deathly Hallows Chapter 19: "The Silver Doe"}