1.
If you see off an opponent, you defeat them. ( BRIT )
There is no reason why they cannot see off the Republican challenge.
PHRASAL VERB : V P n (not pron) , also V n P
2.
When you see someone off , you go with them to the station, airport, or port that they are leaving from, and say goodbye to them there.
Ben had planned a steak dinner for himself after seeing Jackie off on her plane.
PHRASAL VERB : V n P