"When a constituent of NDA takes such a stance, it weakens the fight against Congress and UPA," Mungantiwar told reporters in Chandrapur.
The BJP leader said Shiv Sena's "proximity" to Congress has increased in recent past. "We don't know what will happen in future," he said.
After supporting the UPA Presidential candidate, Shiv Sena today came out in favour of unanimous election of Pranab Mukherjee for the top post, giving a jolt to BJP's plans for a contest.