Explanation

Would" is the correct form for this hypothetical situation.

"Would seek" is used to indicate a hypothetical outcome in a conditional situation.

"If you did not support him, he would seek assistance from some other quarter."

اگر آپ نے اس کا ساتھ نہ دیا تو وہ کسی اور سہ ماہی سے مدد طلب کرے گا۔