Singh will chair a meeting of the BJP Legislature Party which will elect its leader, who will be the chief minister.
Singh was appointed as an observer for Maharashtra after BJP emerged as the single largest party in the assembly polls securing 122 seats out of a total of 288.
Sources said the BJP is in back channel talks with Shiv Sena over government formation and efforts are being made to settle the differences with its oldest ally with whom it snapped ties ahead of polls.
BJP Maharashtra unit chief Devendra Fadnavis continues to be the frontrunner for the post, though there are some more names doing the rounds.
Prime Minister Narendra Modi has called a meeting of all NDA MPs at his residence on Sunday which Shiv Sena members will also attend.
Modi will be in Mumbai on Saturday to inaugurate a private hospital there. It was, however, not clear whether he would have any political meeting during his visit.
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