Samajwadi Party workers celebrate with a poster of Akhilesh Yadav in Allahabad. PTI
The SP, which won a stupendous victory in the recently-held assembly elections, supports the Congress-led United Progressive Alliance from outside.
"Our support should not be taken for granted," Siddiqui said in an interview. His party has 22 MPs in the Lok Sabha.
Siddiqui, who rejoined the party in January this year and is yet to get an official position, said the Congress should support the demand for a financial package for Uttar Pradesh.
"We want to develop UP. UP needs a strong package; it is not growing at the required pace... the centre should help us," said Siddiqui. The previous UPA government did not give any financial package to the state, asserted the leader.
SP chief Akhilesh Yadav, who scripted the party's win of 224 seats in the 403-member house, will be sworn in chief minister on March 15, becoming the youngest chief minister of the state at 38.
Asked how Akhilesh and his father, Mulayam Singh Yadav popularly known as Netaji, would bring development to the state, Siddiqui said the elder Yadav had experience while Akhilesh had a modern approach.
Siddiqui, 62, quit the SP in July 2008 over the Indo-US nuclear deal to join the Bahujan Samaj Party (BSP). He later joined Rashtriya Lok Dal. He had been in the Congress before joining the SP.
In his view, the new political approach of Akhilesh was a key factor in the party's success, The junior Yadav, he said, had "emerged as one of the most popular young leaders of the country".
Asked for the reasons for the poor performance of the Congress and the Bharatiya Janata Party (BJP) in the elections, Siddiqui said they were no longer national parties.
"They are no more national parties but multi-regional parties."
In contrast, the SP has a national outlook and has presence across several states, including Maharashtra, Gujarat, Delhi and Madhya Pradesh, he said.
"The people of Uttar Pradesh wanted change... They have a desire to be part of India's growth story," said Siddiqui, who joined the party after quitting the Rashtriya Lok Dal.
Elaborating on the debacle suffered by the Congress whose leader Rahul Gandhi campaigned extensively in the elections, Siddiqui said Congress leaders "did not understand what the people of Uttar Pradesh wanted."
"Rahul Gandhi failed because he could not get faith of the people. They realised he did not understand UP," Siddiqui said.
Referring to the tenor of Gandhi's speeches, he said "acting as an angry young man" was not the same as understanding the state.
He said voters were not impressed by Congress promises to develop the state as the party was rejected even in family boroughs of Amethi and Rae Bareli and added that there was "media hype about the Congress prospects".
Asked about the possibility of emergence of a third front in the wake of the SP victory in Uttar Pradesh, Siddiqui said West Bengal Chief Minister Mamata Banerjee, Odisha Chief Minister Naveen Patnaik and Bihar Chief Minister Nitish Kumar were trying "to build the front."
"Let us see how it goes. (We have) not given thought to it," Siddiqui said.
Elaborating on the reasons for the rout of Mayawati's BSP in the polls, Siddiqui said disenchantment of Muslims with Mayawati was a factor.
He said the Muslim community realised that even if there were 100 MLAs belonging to the community, they would have no say in a BSP government.
"Muslims realised they were not getting empowered socially and economically," Siddiqui said.
The Muslims had also "returned" to Mulayam Singh, he said.
He said anger among the Muslim community against Mulayam had dissipated after he apologised to them for his decision to take the support of Kalyan Singh before the 2009 general elections. Kalyan Singh was chief minister when the Babri Masjid was razed in 1992.
In the elections, the BSP got 80 seats, the BJP 47 and the Congress could win just 28 seats.
Asked if the party would support the Congress during the presidential polls later this year, Siddiqui said a decision would be taken in due course.