WASHINGTON — One suspicious package went to George Soros, the billionaire investor and liberal philanthropist who is a perpetual target of conservative conspiracy theories and smears — everything from being a former Nazi to the secret financier of the caravan of migrants making its way toward the United States.

Another went to John O. Brennan, the former C.I.A. director often maligned by conservatives as a leading conspirator in a “deep state” plot to undermine President Trump. Hillary Clinton was also sent one, as were President Barack Obama and his attorney general Eric H. Holder Jr. — all of them subjects of fantastical, far-flung rumors and misinformation campaigns.

Law enforcement officials have not identified any suspects or motives in the rash of explosive devices that arrived this week at the addresses of some of the most vilified public figures in Democratic politics. For a country already on edge — consumed with overheated partisan rancor and divided over matters as basic as what separates fact and fiction — the attempted attacks marked an unsettling turn less than two weeks before a crucial midterm election.

[Read more about the devices here.]

But for a moment, at least, the political world paused on Wednesday to urge greater calm in a climate that had become dangerously inflammatory. Speaking at the White House, the president condemned the acts, saying that “acts or threats of political violence of any kind have no place in the United States of America.”