MASTUNG, Pakistan — Hundreds of voters were packed shoulder to shoulder at an election rally less than two weeks ago in a mud-walled village in western Pakistan, listening to the candidates speak, when a white flash ripped across the gathering, followed by a horrible boom.

A suicide bomber had struck the rally in Mastung, Pakistan, in one of the most catastrophic election-related attacks in recent years — 151 were dead, and 177 wounded.

Then on Sunday, in northwestern Pakistan, a suicide bomber blew himself up near a candidate’s car, killing Ikramullah Gandapur, a member of the Pakistan Justice Movement, the party headed by Imran Khan, the former cricket star and contender for prime minister. Mr. Gandapur’s driver was also killed, and three others were wounded, including two police officers.