"Shiv Sainiks put up boards appealing leaders to show self respect. Hope Shiv Sena leadership takes signals and prepare to sit in opposition," Raut said in a post on Twitter.
In another tweet, Raut said media reports indicate that BJP and Sena are discussing 28:14 formula for alliance government. "Is this acceptable to Uddhav Thackeray and why?" he asked.
In an earlier tweet, Raut said the BJP is trying to push Shiv Sena to a corner as much as possible. "Now it's for Uddhav Thackeray to decide how much to bend to come to power," he said.
When asked to comment on Raut's statements, Sena chief Uddhav Thackeray's public relations officer Harshal Pradhan said, "We don't know if Shiv Sainiks have put up boards. Raut is not a party spokesman and does not hold any post in the party."
Back channel talks were said to be on between BJP and estranged former ally Shiv Sena for forming a coalition government.
BJP, which has emerged as the single largest party in the 288-member Assembly with 122 seats, has already been offered outside support by 41-member NCP. With its 63 MLAs, Shiv Sena is the second largest party in the House.