Nitish shot down Lalu's plea - made on Thursday and repeated on Friday- word for word in a first for the two since they teamed up to form the Grand Alliance government in Bihar.
"I also take pride at Meira Kumar being Bihar ki beti but is the daughter of Bihar being fielded to defeat her?" Nitish told reporters after attending an iftar party at Lalu's 10 Circular Road residence. "Everybody knows the outcome of this (presidential) election."
The chief minister stressed that Kovind did not have an RSS background and had started his political career with Morarji Desai, and urged the national Opposition to review its strategy.
"They should actually have a strategy to win the 2019 elections and make her (Meira Kumar) the President in 2022," Nitish said, said stressing that he had spoken to Lalu this morning.
He insisted that his support for Kovind "is not related to the Grand Alliance government" and pointed that even when he was in the NDA he had opposed the BJP's remarks against the President and the Vice-President.
"If I am making a historic mistake, so be it," Nitish declared in an obvious reference to Lalu's appeal to the chief minister not to make a "historic blunder" by backing Kovind.
Asked whether his decision would not affect efforts for Opposition unity, Nitish said any bid should be towards ensuring a win.
"Unity efforts should be directed towards winning in 2019 (when the Lok Sabha election is due)," the chief minister said.
At Lalu's iftar event, Nitish and Lalu "acknowledged each other but the atmosphere was tense," said someone who was there.
Earlier in the day, Lalu again appealed via the media to Nitish to rethink his support for Kovind.
The RJD chief, who arrived here this morning from Delhi, reminded the chief minister of his own call - before the Bihar Assembly elections in 2015 - for a " Sangh-mukt Bharat" (country free of the Sangh parivar).
"We are following the path you showed," he told reporters at Patna airport, addressing Nitish.
During the first two meetings of the Opposition in Delhi on the presidential polls, the JDU and Nitish had said they would go with whatever decision is taken, Lalu said, adding: " Jane kya khichdi paka (I don't know what transpired), why he changed his stand."
"Ram Nath Kovind is from the Koli caste. Kolis (also known as Koris) are on the Dalit list in UP but in Gujarat they have been bracketed as a backward caste. In Gujarat they have a sizeable population of over 12 per cent. PM Narendra Modi and BJP president Amit Shah, while naming Kovind, have the Gujarat elections in mind because the Patels are angry with the BJP," Lalu said.
Lalu pointed out that Kovind was a witness for Bangaru Laxman, the then BJP president who was caught accepting bribe in a sting by news magazine Tehelka.
JDU insiders said they feared that Lalu will continue to "embarrass" Nitish by playing the Dalit and Bihar ki beti cards again and again till the presidential polls are held in mid-July.
For now, both the JDU and the RJD are stressing that the Grand Alliance stands united despite the differences. But the question that is increasingly gaining currency in political circles is: For how long?
"Nitish Kumar has already crossed the line by defying the appeals of all the opposition parties and Lalu and Nitish have gone public for the first time against each other. It is virtually a point of no-return," said a senior RJD leader.
If Lalu's sons are charged in the ongoing investigation into the assets of Lalu and family, Nitish may ask for Tej Pratap and Tejashwi's resignation and that will be the breaking point, feel many political insiders.
Speculation that Nitish is warming up to his old ally BJP has been swirling even before Kovind's name was announced. "It appears Nitishji wants out," admitted a JDU leader.
The chief minister has called for a meeting of Grand Alliance leaders on July 2 to "discuss the political situation".
The BJP on its part ridiculed Lalu.
"The UPA was in power at the Centre for 10 years and they did not remember Dalits then," said senior BJP leader Sushil Kumar Modi. "They made Pratibha Patil and Pranab Mukherjee Presidents. Why did they not remember Jagjivan Ram's daughter then? It was only after BJP announced the name of Ram Nath Kovind that they remembered Dalits."
-The Telegraph Calcutta