How does the united nations engage in campaigning to resolve public issues?

The United Nations usually have votes in their council and the security council if there are public issues that present a real problem. The countries that are the ones with the problems should usually adhere to these decisions if they want to avoid things like economic and political sanctions. They campaign for these decisions by having countries who are members support it publicly and spread the idea of preventing such issues.

The president's only official legislative duty is to sign or veto bills.