Mr Tyagi said Mr Kumar had informed Prime Minister Narendra Modi about various initiatives of his government during their meeting on August 11. The two are slated to meet again in the last week of this month.
"The chief minister told the prime minister that expectations of the people of Bihar have risen (after Nitish joined hands with the BJP). They want developmental works to be done quickly. Modi was positive," Mr Tyagi told reporters.
The prime minister's office, he said, has begun working on projects concerning Bihar.
Mr Kumar has made 'saat nischay' (seven resolves), which include taking power, drinking water and drainage link to every household, besides building toilets. These were part of the agenda of his government after coming back to power in 2015.
"Since the alliance ruling the state and the Centre are the same, we expect that a Bihar package will soon be executed. Bihar's 'achhe din' (good days) will soon come," he said.
He noted that the Bihar Assembly had passed a resolution seeking central assistance for the state, and an all-party delegation of MPs had met former prime minister Manmohan Singh in its support.
Mr Kumar was heading the rival alliance of the Janata Dal United-RJD-Congress when the Prime Minister had promised a package of Rs 1.25 lakh crore for the state.
In a dramatic turn of events, he jettisoned the alliance last month and joined hands with the BJP.
The projects listed by the Bihar chief minsiter include building roads and drainage that will cost Rs 78,000 crore, electrification schemes costing over Rs 55,600 crore, and those related to drinking water and toilets involving expenditure of Rs 47,700 crore and over Rs 28,700 crore.
Mr Tyagi said JDU's national executive will ratify a proposal to formally join the NDA at a meeting of its national executive on August 19 in Patna.