ALBANY — The capital was thrown into familiar tumult on Monday as yet another of the state’s leaders fell from grace: Dean G. Skelos, the majority leader of the New York State Senate, stepped down from his leadership post.

The announcement followed a week of escalating pressure on Senator Skelos, who sought to stay on as the chamber’s leader despite his arrest last week on federal corruption charges. To succeed him, Republicans selected John J. Flanagan, who, like Mr. Skelos, is from Long Island.

“It was the right decision to step aside,” Mr. Skelos said, adding, “I was a distraction.”

His downfall adds a chapter to what has already been a difficult year in Albany. In a span of only 16 weeks, the leaders of both legislative chambers have been arrested and replaced as a result of separate corruption cases, a head-spinning change in a capital known for its inertia.

Mr. Skelos’s decision on Monday came after his counterpart atop the State Assembly, Sheldon Silver, was forced to give up his post as speaker after his own arrest on federal corruption charges in January. In a similar series of events, Assembly Democrats first rallied around Mr. Silver, before deciding days later, amid calls for his ouster, that he could no longer continue as speaker.