It all started last evening, when the Aam Aadmi Party (AAP) chief needled Mr Singh after the Congress leader accused him of deliberately fielding a weak candidate against Chief Minister Parkash Singh Badal as part of a secret understanding with the ruling Akali Dal.
Mr Singh's instant response was a direct dare to the Delhi Chief Minister to contest against him.
Sir, r u fighting against Prakash Badal ji or sukhbir Badal or Majithia or safe seat? https://t.co/ceSoAxNPn8- Arvind Kejriwal (@ArvindKejriwal) December 28, 2016
Mr Singh, a former Chief Minister of Punjab, is the face of the Congress for the polls. Mr Kejriwal's response to his dare came this morning.
Badals' story is over. You tell me where you're contesting from and I will come fight you there! https://t.co/rpghXJoSwo- Capt.Amarinder Singh (@capt_amarinder) December 28, 2016
So, u r fighting me, not Badals/drugs. Badals also say they will fight against me. U n Badals wish to fight agnst me not agnst each other https://t.co/VXtZrIlgqs- Arvind Kejriwal (@ArvindKejriwal) December 29, 2016
The two leaders have sparred on Twitter before. In October, they challenged each other to an open debate in the run-up to the polls.
I m not fighting punjab elex. So, ur challenge hollow. We r fighting Badals/Majithia, who sunk Punjab in drugs. N u r fighting us, not them? https://t.co/yxtvCGv0Xo- Arvind Kejriwal (@ArvindKejriwal) December 29, 2016
Mr Kejriwal has alleged that the Akalis and the Congress are fighting the election together and the ruling party is funding the Congress' campaign with "drug money" - an indirect reference to state minister Bikram Singh Majithia, who faces allegations of drug-smuggling.