Here are the latest developments in this big story.
The well-known unpredictability of Goa's politicians apart, senior Congress leaders admitted today that defeating Manohar Parrikar on the floor of the state legislature appears to be a difficult task.
Hours before the vote, Vijai Sardesai, leader of regional party Goa Forward told NDTV that the Congress has been "trying to reach out through friends." Mr Sardesai said his party "will not backstab" Mr Parrikar who "resigned as Defence Minister to come here."
Goa Forward has pledged the support of its three legislators to the BJP as has another regional party the MGP, which too has three MLAs. They have been rewarded with multiple cabinet posts - of Mr Parrikar's nine new minsters, only two are from the BJP, apart from the Chief Minister himself.
The Congress appeared to count much on how three Independent legislators would vote, but two of them - Govind Gaude and Rohan Kaunte - have already taken oath as ministers and told NDTV they would vote for Mr Parrikar. It has tried to convince the third Independent MLA, Prasad Gaonkar and also Goa stalwart Churchill Alemao of the Nationalist Congress Party to vote against Mr Parrikar, but that will not be enough to defeat the BJP.
The Congress is Goa's single largest party with 17 seats but was slow in moving to secure the support of four more legislators that it needed for a majority. The BJP quickly tied up its alliance and staked claim to form government.
The Congress is now struggling to keep its own flock together with several legislators accusing the party's senior leader in charge Digvijaya Singh of "mishandling" Goa. A vocal critic Viswajeet Rane said he would vote for the Congress today, but hinted that he might not stay with party thereafter.
Ahead of the trust vote today, the Congress wrote to Governor Mridula Sinha objecting to BJP legislator Sidharth Kuncalienker being named Pro-Tem Speaker - a temporary post - instead of convention being followed of the seniormost legislator in the assembly being appointed.
The Congress' Pratap Rane, 78, is the most senior MLA. Mr Kuncalienker is in his 40s. A Pro-Tem Speaker is appointed to run activities of the legislature when a regular Speaker hasn't been elected.
Manohar Parrikar resigned as the country's Defence Minister earlier this week to take over as Goa Chief Minister, a condition laid by the BJP's new allies for their support.
In elections held in five states, the BJP swept two - Uttar Pradesh and Uttarakhand - and while it came second to the Congress in Goa and Manipur, it managed to form governments in both by securing the support of smaller parties. A win in Punjab was the Congress' consolation prize.