BUDAPEST — The annual Independence Day celebration at the United States Embassy in Budapest is usually a modest garden party, a chance for the ambassador to celebrate American freedom, democracy and the rule of law.

This year, the ambassador, David B. Cornstein, spent hundreds of thousands of dollars on a blowout gala for 800 guests. He flew in the singer Paul Anka from California. The guest of honor was Prime Minister Viktor Orban of Hungary, who has curtailed the very freedoms the event was meant to highlight.

Standing at a lectern, Mr. Cornstein declared Mr. Orban “the perfect partner” and “a very, very strong and good leader.” Mr. Anka serenaded the Hungarian leader with a personalized rendition of “My Way.”

For many in the room, it was a bewildering spectacle: an American ambassador lavishing praise on a far-right leader whose party has methodically eroded Hungarian democracy and pushed anti-Semitic tropes. But it was just another demonstration of Mr. Cornstein’s pattern of emboldening Mr. Orban.