Mamata Banerjee said she received an invite and that she will try to attend PM Modi's oath ceremony

Highlights Mamata Banerjee has accepted PM Modi's invite to his swearing in

She called the ceremony a "constitutional obligation" she'd try to fulfil

PM Modi, Ms Banerjee have fought a bitter national election in Bengal

Mamata Banerjee on Tuesday said she would try to attend Prime Minister Narendra Modi's oath ceremony in Delhi on Thursday, since "it is a ceremonial programme". The Bengal Chief Minister's RSVP surprised many on a day the ruling BJP flaunted a large group of defectors from her Trinamool Congress and threatened more switches. For Mr Modi's second oath ceremony, several world leaders, chief ministers and opposition leaders have been invited. Among them are Delhi Chief Minister Arvind Kejriwal and Telangana Chief Minister K Chandrashekar Rao, who have accepted the invitation.

"I have spoken to other Chief Ministers also. This is a ceremonial program. There are certain constitutional obligations that we try to fulfil. We will try to attend the event," Mamata Banerjee said.

After a bitterly fought national election in which the BJP ended up with 18 seats in 42-seat Bengal - only a few less than the state's ruling Trinamool that dropped from 34 in 2014 to 22 - the BJP on Tuesday made it clear that the battle was not over.

Two Trinamool lawmakers and over 50 municipal councillors, mostly from Mamata Banerjee's party, joined the BJP on Tuesday in what the party called the first of a many-part exodus. Senior BJP leader Kailash Vijayavargiya reminded Mamata Banerjee of PM Modi's campaign speech that "over 40 Trinamool MLAs (legislators)" were in touch with the BJP.

"The elections in Bengal were held in seven phases. Now these joinings (sic) from Trinamool will also take place in seven phases. Today was the first phase," said Mr Vijayavargiya, with former Trinamool leader Mukul Roy seated beside him.

Mukul Roy was a close aide of Mamata Banerjee before he was removed in 2017. He joined the BJP.

Mukul Roy's son Subhrangshu was among those who joined the BJP on Tuesday.

The BJP's challenge, and the exodus from Trinamool, indicates the party's plan to consolidate its national election victory and extend it to 2022, when the assembly elections to Bengal will be held.

Mamata Banerjee, stunned by her party's steep decline in Bengal and the BJP's equally sharp rise, had said on Saturday that she wanted to resign but had been persuaded by her party to stay. The furious chief minister accused PM Modi and BJP chief Amit Shah of harassing her government, blocking its work and creating an "emergency-like situation" to win the Bengal polls.