Though there has been no official confirmation as to why Lamba was suspended, news reports suggest that she was suspended after she admitted that Delhi chief minister Arvind Kejriwal asked Rai to step down.
According to reports, it is said that the party believes that Lamba deviated from party line as she told reporters that Rai had been relieved as the Delhi Transport minister.
Lamba had made the comments outside the Anti-Corruption Branch's (ACB's) office, where she had gone to extend support to Rai.
While AAP said that Rai was resigning due to health reasons, Lamba said that chief minister Arvind Kejriwal wanted to ensure a fair probe into the corruption charges against Rai and hence asked him to step down.
Meanwhile, Rai had earlier said that he was ready to go to jail if corruption charges made against him were proved.