The drive to oust Prime Minister Naoto Kan gathered steam Monday as speculation grew that key members of his party would join forces with the opposition to submit, possibly as early as this week, a vote of no confidence to the Diet.

For the motion to succeed, more than 80 lawmakers from the ruling Democratic Party of Japan would have to sign on, perhaps opening the door to party heavyweight Ichiro Ozawa, a former DPJ leader who must now decide whether to take charge and cooperate with the opposition parties to bring Kan down.

Deputy Chief Cabinet Secretary Yoshito Sengoku on Monday morning tried to forestall the drive by arguing that changing leaders will do nothing to help the nation recover from the nuclear crisis.