The party, which failed to persuade allies like Shiv Sena and JD-U to support Sangma, argued that it was its duty as the main Opposition party not to allow a "walkover" to Congress which did not "consult" it.
Announcing the decision at a press conference, BJP leaders Sushma Swaraj and Arun Jaitley said the main opposition party could not support a government which is using "various manoeuvres", including investigative agencies, to rope in parties to stay in power.
"BJP has decided to support the candidature" of Sangma, whose candidature has been proposed by AIADMK and BJD, Swaraj said.
Describing Sangma as "the country`s tall leader" as also North East`s "tallest leader", she appealed to allies like Shiv Sena and JD-U to give up their opposition to his candidature.
Swaraj and Jaitley regretted that BJP could not persuade its allies and have a consensus in the NDA over the issue but insisted that it would have no impact on the "mature" coalition.
To press her point, she noted that Shiv Sena had earlier also voted for UPA nominee Pratibha Patil during the last Presidential poll even though NDA had opposed her candidature but still remained part of the alliance.
Swaraj and Jaitley said BJP was trying to bring Trinamool Congress on board but refused to reveal how it was being done.