One of the largest arguments against the US leaving the UN is because of it's status as one of the 5 permanent members of the UN Security Council. Should the US leave, it would loose veto power for proposals introduced by Russia and China, and as such would have to curry favour with France or Britain to veto the proposal.

This hurts American interests as it's unlikely that Britain or France would change it's mind about supporting a proposal unless the US gives them something in return.

Another argument against it would become blindingly obvious if you ever visit the UN and talk to one of the tour guides. Hundreds of thousands of meetings take place each year in the various UN buildings. They're one of the greatest tools of International diplomacy ever conceived. Should the US leave, it would have no standing or say in the meetings that take place, only allowed to offer an opinion that the rest of the UN are completely free to disregard entirely.

One of the largest arguments against the US leaving the UN is because of its status as one of the 5 permanent members of the UN Security Council. Should the US leave, it would lose veto power for proposals introduced by Russia and China, and as such would have to curry favour with France or Britain to veto the proposal.

This hurts American interests as it's unlikely that either Britain or France would change their minds about supporting a proposal unless the US gives them something in return.

Another argument against it would become blindingly obvious if you ever visit the UN and talk to one of the tour guides. Hundreds of thousands of meetings take place each year in the various UN buildings. They're one of the greatest tools of International diplomacy ever conceived. Should the US leave, it would have no standing or say in the meetings that take place, only allowed to offer an opinion that the rest of the UN are completely free to disregard entirely.