Mr. Ferguson's decision comes less than two weeks after Representative Jim Saxton, a Republican who has represented New Jersey's Third Congressional District for more than two decades, said he would not seek re-election because of health concerns.
Last year was the first in decades with no member of the Kennedy family in federal office, after Representative Patrick Kennedy gave up his House seat representing Rhode Island.
Mussolini sent his after representative called to see Pope's.
In 2011, there was a move to détente after Representative Gabrielle Giffords of Arizona was shot.
Immediately after, Representative Joseph Kennedy III delivered the official Democratic response with an eerily familiar sense of frightened urgency.
The letter was publicized after Representative Boehner, Republican of Ohio, issued a strongly worded statement criticizing the G.A.O.
By then he had declared his candidacy for a full term, but well after Representative Max Baucus had done so.
South Dakota has held only one such special election, in 1908, after Representative William H. Parker died in office.
In Thursday night's debate, Vice President Joe Biden will almost certainly go after Representative Paul Ryan's Medicare plan.
But soon after Representative Robert E. Andrews arrived, an organizer took him aside, at the urging of Mr. Lautenberg's assistants, and asked him to leave.
Representative after representative told the story of a constituent who had died of gun violence — stories that they did, indeed, seem to believe demanded some attention.
