The Opposition BJP has challenged the merger of the BSP legislative party with the ruling Congress in Rajasthan.
It was in September last year that all six Bahujan Samaj Party MLAs in the state had joined the ruling party.
A group of 20 BJP MLAs, led by party's state president Satish Poonia, met the Assembly Speaker CP Joshi on Friday, submitting a petition against the merger.
"It was the decision of the MLAs, who won the elections in the state on the BSP ticket. There was no merger of the BSP with the Congress at the national-level. Therefore, the merger should not be held valid," Mr Poonia said.
The state BJP chief said the speaker told them that he would look into the constitutional aspect of the matter.
In a politically significant development, the merger had lent more stability to the Ashok Gehlot government in the state, increasing the Congress' tally to 107 in the 200-member assembly.
Those who joined the Congress were Rajendra Singh Gudha, Jogendra Singh Awana, Wajib Ali, Lakhan Singh Meena, Sandeep Yadav and Deepchand.
The ruling party also enjoys the support of 12 of 13 Independents.