Samajwadi Party today dubbed as "unconstitutional" the bill to provide reservation in promotion for Scheduled Castes and Scheduled Tribes in government jobs and threatened to oppose the measure tooth and nail. Soon after the introduction of the bill in Rajya Sabha amid scuffle between Samajwadi Party (SP) and Bahujan Samaj Party (BSP) members, SP chief Mulayam Singh Yadav said the bill is "unconstitutional in nature. We will continue to oppose it with all our might."