The self-avowed Hindu nationalist, four days short of his turning 63 years, was anointed at a meeting here of the 12-member BJP Parliamentary Board which a sulking Advani skipped.
The announcement was made by BJP chief Rajnath Singh after the meeting which was attended by Murli Manohar Joshi and Sushma Swaraj, who too were said to be opposed to Modi's projection at this juncture but finally toed the majority line.
He said the country is going through a "crisis" and BJP would require blessings of people from Kashmir to Kanyakumari and Attock to Cuttack so that this situation ends.
Thanking party leaders and NDA allies for their support, the three-time Gujarat Chief Minister said will work tirelessly to ensure that BJP wins the 2014 elections.
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However, Advani touched a sour note by releasing an angry letter written by him to the party chief almost at the same time when announcement about Modi was made.
"I had told you that I will think whether I should share my thoughts with other Board members or not. Now I have decided that it is better that I do not attend today's meeting," he wrote.
Soon after the announcement, Modi met Advani to seek his blessings. During the 30-minute meeting, Advani obliged him but also asked him about the letter written by suspended IPS officer D G Vanzara who quit service while attacking Modi.