Something weird is happening in Nagaland - NPF just gave away a seat to its non-existent alliance partner congress, which it won in 2018 assembly election, for contesting in the bypoll, necessitated demise of the sitting NPF mla.
So here is some peek into how did we get here.

2013 - NDF and bjp gov cruse their way into reelection, on the back of the popularity of sitting cm Neiphiu Rio, who have been cm since 2002.
Ndf +bjp - 39 seats
INC(main opposition party) - 8 seats

In 2014, Neiphiu Rio thought that new nda would negotiate the new peace treaty and he wanted to have a stack in it, so he quit his cm post and constested lok sabha election, which he won easily.
NPF nominated T. R. Zeliang as their cm.

Zeliang immediately went on to initiate merger of opposition mla's into npf, so as to boost his own supporters in the assembly. Soon the assembly was opposition less after 4 ncp and 8 cong leaders joined npf.

Remember npf have relatively more inter-party democracy than u would see in a typical Indian political party. So what Zeliang was made some sense and it worked only for a small time.

Because 2 things happend
1st) naga peace treaty was going nowhere, so Neiphiu Rio was becoming desperate to come back state politics and once become cm.
2nd) In 2017 zeliang proposed something which proved to be deeply unpopular in the state.

And that something women reservation in panchayat polls. U see not all northeastern tribes are matriarchal, some of them are deeply patriarchal, naga tribe is one of the latter. So when government proposed reserving where only women could contest, in other words

Tribal heads couldn't contest because all of them were male, they hit the streets to show their frustration, which already growing because central government was no mood to made naga peace treaty public, which they declared as a done deal in 2015.

Zeliang had to resign as a CM in Feb 2017, someone named Shürhozelie Liezietsu took office. Now remember those ex- ncp ex-cong mlas who joined npf gov. well they wanted zeliang back as cm. So zeliang was back as cm within 6 months in July 2017.

This frustrated Neiphiu Rio, and he went on to form his political party, NDPP before 2018 assembly election. Bjp which have been NPF's alliance partner since 1990s dumped them and joined NDPP to fight assembly election togather.

And NDPP +BJP combine, won the election, Rio became cm again. Total seats - 60
NDPP - 19
BJP - 15
Ndf - 26
Cong - 0 (vs - 2.1%)

And this whare our story gets weirder, come 2019 LS election NPF gave the only lok sabha to congress, without getting anything in return.
Congress gave the ticket to ex - cm KL chishi.
And surprising thing is cong performed really well. Congress led in 28 assembly segments.

One of the rumors going around was sharmaji beech rasteh meh paisa kha gaye as a justification for bad show by NDPP and bjp alliance.
Now fast forward to today - two seats in assembly got vacant due to demise of sitting mlas (one npf and another ndpp).

Instead of keeping the npf seat for themselves, they gave away the seat tk cong for contesting, while keeping the ndpp seat to themselves(which will be much harder to win, because it comes under influence area of CM)

Cong ls candidate lead the npf seat by 3k votes, but thats because of bpf support only.
So why is npf propping up the cong?
That's anybodies guess.

But my guess would be, that pre-2018 npf is like pre - 1969 cong.
In 18 they just lost their own Indira, now they falling apart like pack of cards. Propping up cong is a insurance for Zeliang and his gang.
End.