Prime Minister Manmohan Singh is yet to give an appointment to the JD(U) delegation, which is carrying with it 1.25 crore signatures to be submitted to him to press the demand for special state status to Bihar.
"It is unfortunate that the PM has not confirmed an appointment with the delegation," ruling JD(U) spokesman Sanjay Singh said.
Both JD(U) and Chief Minister Nitish Kumar had sought an appointment with the prime minister on several occasions but no response was received, he said.
"The delegation is ready to submit a memorandum to the PM on July 13 in support of the demand... We hope to get a positive response."
Kumar had on Sunday flagged off 26 vehicles - an air conditioned rath and other vehicles carrying over 1.25 crore signatures of the people of Bihar.
The 121-member delegation includes Bihar JD(U) president Vashisth Narayan Singh, MPs RCP Singh and Monazir Hasan, a number of MLAs and leaders of various fronts of the ruling party.