"Gurumurthy BJP's CAG?" Singh said in a Twitter post.
On Wednesday, the Congress leader slammed Gadkari, who is accused of improper business dealings and under pressure within his party to quit, saying the latter had defended former Karnataka Chief Minister BS Yeddyurappa over the corruption issue.
Singh tweeted: Gadkari on Yedurappa corruption 'Immoral but not illegal'. BJP response to Gadkari's fraud companies 'Neither Illegal nor Immoral' Jai Ho BJP."
Meanwhile, the BJP remained fragmented despite the party's core group giving a clean chit to Gadkari over the functioning of his companies. BJP MP Ram Jethmalani had sought Gadkari's immediate resignation with apparent support of some senior BJP leaders.
The veteran lawyer-turned-politician had also shot a letter to LK Advani over the matter and believed that the BJP's fight against corruption would be discredited if it continued to carry the Gadkari baggage. Jethmalani's son Mahesh also quit from the BJP national conference saying he was not ready to serve under Gadkari.
Digvijay Singh also said that his admiration for Advani had gone up for his principled stand on Gadkari. He also wished the veteran BJP leader who turned 85 on Thursday.