"If Upendar Kushwaha said 'no' to joining the Grand Alliance, his 'no' means 'yes'. Try to understand it. He will join Grand Alliance soon," Mr Manjhi told reporters.
Mr Kushwaha is one of four major components of the coalition led by the BJP in Bihar. Ahead of the national election, now less than a year away, the BJP in Bihar finds that its partners are using its recent electoral setbacks to negotiate hard for how the state's 40 parliamentary seats should be divided up.
On Saturday, Bihar's opposition leader Tejashwi Yadav issued an open invitation to Mr Kushwaha to quit the NDA and join hands with the opposition.
However, the junior minister of Human Resource Development on Sunday denied reports that he was contemplating joining the RJD-led alliance. He said the RLSP will be a part of the NDA in the 2019 polls.
(with IANS inputs)