Hey,

Yes you can go for admission into political science courses even if you don't have political science in your class 12th.

The colleges which accepts admission on merit based on the percentage in class 12th like DELHI UNIVERSITY, they provide admission to students of other streams in arts stream.

There will surely be a deduction in your percentage as a penalty because you haven't studied political science and after the deduction if you met the cut off you will be given admission.

Hope that helps.

Thank you