At least 75 people were killed in the attacks.
A bomb-laden car parked near a Ramadan celebration exploded around noon in Kaduna, killing 25 people.
An investigation into the remote-controlled explosion is looking into whether Muslim cleric and vocal critic of terrorism, Sheikh Dahiru Usman Bauchi, was the target. "His convoy escaped the bomb blast by whiskers," Nigeria's Department of State Security acknowledged.
A second bomb detonated hours later at a crowded bus stop in the town of Kawu, reportedly targeting opposition leader and former military dictator Muhammadu Buhari. 50 people were believed to have died in the second bombing.
There was no indication that Buhari was injured in the attack.
Wednesday's attacks were launched outside Boko Haram's stronghold in the northeast, and demonstrate a growing trend of terror attacks throughout the country.
The U.S. Department of State issued a statement condemning the attacks and the targeting of religious and political leaders.
"We call on Nigerian authorities to fully investigate these attacks, and we urge all Nigerians to avoid reprisals and continue to practice the interfaith cooperation that violent extremists seek to undermine."