Amit Shah, 54, took oath after days of speculation whether he would become part of the government.

Highlights As BJP chief, Amit Shah was the architect of party's landslide win

Took oath along with PM Modi, 56 ministers on Thursday

Became the most prominent newcomer in PM Modi's government

BJP chief Amit Shah -- the architect of the party's stupendous victory that enabled it to come to power at the Centre for a second term -- became the most prominent newcomer in the government of Prime Minister Narendra Modi in its second stint. PM Modi and his council of ministers took oath on Thursday at a grand ceremony at Rashtrapati Bhavan that was attended by world leaders, celebrities and political leaders.

Mr Shah, 54, took oath on Thursday after days of speculation whether he would become part of the government. A section in the BJP wanted him to stay on as the party chief as assembly polls in a string of states come up later this year, and elections in Delhi and Bihar the next.

Over the last two days, Mr Shah had two marathon meetings with PM Modi - once for five hours and once for three - to deliberate on the contours of the council of ministers, balancing out representation of states and sections, demand of allies, reward to successful party colleagues, and gratitude to new states that overwhelmingly voted for the party.

This, though, was not the first time there was speculation on whether Mr Shah - once the home minister of Gujarat - would take on the responsibilities of governance nationally.

The question came up after the ace-politician catapulted the BJP to power nationally in the 2014 general elections,, but Mr Shah had made it clear that he was not ready to take a hand in statecraft yet. Asked the same question when he entered the Rajya Sabha, he had laughed it off, saying, "Don't push me".

Mr Shah's meteoric rise in the party had taken less than a decade. In 1991, he got his first big break, managing the campaign of BJP patriarch LK Advani from Gandhinagar during the Lok Sabha elections. But his political acumen came into full play as he became a close aide of Narendra Modi. He was even considered a possibility for the top post in Gujarat when Narendra Modi moved to national politics.

Mr Shah, however, moved to Delhi along with PM Modi, making Congress-Mukt Bharat (Congress-free India) his mission. Today, Mr Shah has almost reached his goal, though a combination of electoral victories, smart alliances and acquisition of assets - key leaders of rival parties.

The BJP now controls most of the north and west and whole of the northeast. In the east, it controls Bihar and made huge inroads into Mamata Banerjee-ruled Bengal and posted significant gains in Naveen Patnaik's Odisha.

While the Congress managed to wrest the heartland states of Rajasthan, Madhya Pradesh and Chhattisgarh, the BJP's spectacular performance in all three states in the Lok Sabha elections has brought fresh cheer to the party.

The haul of new seats helped it zip past the 300 mark in the Lok Sabha -- way above its 2014 tally of 282 seats -- and deliver another crushing defeat to the Congress.

It is not known yet whether Mr Shah will balance his cabinet portfolio with the party post. For now, the focus is on his new stint as a minster of NDA 2.0.