The Secular Progressive Front is led by Congress's Ibobi Singh.
The Congress has moved a no-confidence motion against the Biren Singh-led government Manipur a day after nine legislators withdrew support from the government. If the government fails to survive, the BJP will lose the northeastern state where it formed a government in 2017 despite the Congress emerging as the largest single party in the election.
In the 60-member assembly, there are eight Congress MLAs who supported Biren Singh in 2017. One is already disqualified and seven others have been barred by the Manipur High Court from the assembly premises till the Speaker gives a final decision on their disqualification.
Three BJP MLAs have also now resigned, all of which brings down the effective strength of the house to 49. The majority mark will be 25.
Of the 49 MLAs, the BJP has the support of 23, the Congress has the support of 26.
The no-confidence motion was moved after the Manipur unit of the Conrad Sangma-led National People's Party or NPP -- a key BJP ally in the northeast --formed an alliance with the Congress.
The new alliance, called the Secular Progressive Front or SPF, also has the support of one Trinamool Congress and one Independent MLA.
The SPF, which is led by former Chief Minister Okram Ibobi Singh, has urged the Governor to call a special assembly session for the floor test.
Starting with Assam in 2016, the BJP had managed rule all eight states in the northeast -- singly or in alliance with local parties. If the Bikram Singh government loses the trust vote, it would be the first state in the area to slip out of the BJP's grip.
The ascendant numbers on the Congress side will also create trouble for the party in the June 19 election for the lone Rajya Sabha seat in the state, which is currently held by the BJP. The candidate who gets the maximum number of first preference votes will win. Cross voting, however, is allowed in the Rajya Sabha.
Among the nine MLAs who withdrew support from the government, four are from Conrad Sangma's NPP, who include Deputy Chief Minister Y Joykumar Singh, cabinet ministers N Kayisii, L Jayanta Kumar Singh and Letpao Haokip.
Three BJP MLAs -- S Subhashchandra Singh, TT Haokip and Samuel Jendai – the lone Trinamool Congress MLA T Robindro Singh and Independent MLA Shahabuddin are also among the rebels.