BAGHDAD — A vice president of Iraq, a prominent Sunni Muslim, was convicted of murder and sentenced to death on Sunday in a trial conducted in absentia. The verdict coincided with a wave of bombings and insurgent attacks that claimed at least 100 lives, making Sunday one of the bloodiest days in Iraq since American troops withdrew last year.

Together, the verdict and the violence threatened to deepen an already intractable political crisis among the country’s ruling factions.

Sunni leaders who support the vice president, Tariq al-Hashimi, responded angrily to the court’s action, accusing the Shiite-led government of trying to sideline them from a power-sharing arrangement meant to guard against the sectarian violence that continues to plague the country.

Attacks were reported in at least 10 Iraqi cities on Sunday, including Shiite neighborhoods of Baghdad, where two markets, a restaurant and a crowded square were struck, capped by a car bomb that exploded late in the evening in Sadr City, a Shiite stronghold in the capital. The attacks underscored the increasing potency of insurgent groups in Iraq, which appear to have blossomed amid the political paralysis that followed the American departure. Their attacks have tended to come in coordinated waves across the country, including the attacks by Sunni extremists on July 23 that killed about 107 people and appeared to reflect a spillover of sectarian strife from neighboring Syria, and the car and roadside bombings of Aug. 16 that killed about 100, including dozens at an amusement park in eastern Baghdad.