Samajwadi Party and Shiv Sena today thwarted an attempt in the Rajya Sabha to take up for passage the contentious Bill providing for quota in promotion for SCs and STs in government jobs. The Constitution Amendment Bill, which was introduced in the House yesterday amid commotion and scuffle between members of SP and BSP in the House, could not be taken up even as Minister of State for Personnel V Narayanasamy rose to move it for consideration and passage.