NPF chairman Shurhozolie Liezietsu has written to Shah, saying they were "still friends".
Yepthomi was seen with NDPP leaders during the day but he refused to comment on this.
The NDPP-BJP alliance on Sunday met Nagaland Governor P B Acharya and staked claim to form the next government in the state.
After meeting Zeliang, Acharya told that Rio and Zeliang have claimed to have majority support, but "I have not invited anyone to form the Government as of now".
In 2013, the BJP had won one seat with 1.8 per cent vote share to the NPF's 38 seats with 47 per cent vote share.
While the fight between the NDPP and NPF remained neck and neck, it is the decisive seat gain for the BJP party.
"The BJP will form the government in Nagaland with the help of other parties", he told PTI here. Such a coalition government is likely to be more stable and lead to a more cordial and congenial political atmosphere in the region. "It is good for the Northeast, good for India", he said.More news: Gun-related injuries decrease during NRA conventions, study finds
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Political analysts in the state had also largely predicted the NDPP-BJP alliance will form government.
Zeliang has expressed hope of gaining the support of the BJP to form the Government, he said.
The figures at 6.30 pm indicated that the NPF had won 27 seats and its allies - Conrad Sangma's National People's Party and Janata Dal (United) had won one each.
The issue was referred to the Election Commission on Saturday night. This took place in the presence of Union Health Minister Jagat Prasad Nadda and BJP National General Secretary Arun Singh.
"We (BJP and NDPP) had detailed discussion on the architecture and representation of the two parties in the government".
Asked whether the BJP's decision to sever ties with the NPF would impact their relationship in Manipur, where four NPF legislators are part of the BJP government, Kikon said, "The NPF will have to revisit the decision". On being asked if Zeliang has been official notified by BJP, Sarma said, "In politics you don't go by too many letters; politics goes on signal, and we have send enough signals to Mr. Zeliang that at this stage we can not be friends with NPF". From a call to boycott the polls before a solution to the vexed Naga insurgency issue to the church issuing a diktat not to "pierce the heart of Jesus" by voting the BJP to power, the state saw it all.
Liked the story? We're a non-profit. Sources said it would soon be clear how many ministerial berths the party would have in the new dispensation.