I think the issue here is whether the federal government can pressure a local government to assist with the federal government's duties or lose federal funding. In a similar recent situation, the supreme court ruled against the Feds. It stated the Obama administration cannot withhold traditional medicaid funding in order to force some states to accept the medicaid expansion under Obamacare. There are many reasons why a local government may resist helping the feds. Politics is a big one, but there are valid ones as well. If a local government is perceived as overly helping the feds, then the illegal immigrant communities would not come forward and assist with law enforcement. Not to mention that figuring out who is legal and who is not is not always straightforward.

Lebanon has always been a mess with shifting political alliances all over. However, I heard there was an agreement almost 2 years ago between Aoun and Hariri that Aoun would become president and Hariri PM. I think the Americans and Saudis balked at the time. Recently, Hariri and his supporters lost big time in Tripoli's municipal elections and almost lost Beirut (their main stronghold). They would have lost Beirut had it not been for the fact that Aoun and his party and Hezbollah did not challenge them. Hariri had no choice: either accept Aoun as president and himself become PM or continue to slide in the Sunni street. For Aoun and hezbollah, it was probably easier to deal with and sustain a weakened Hariri rather than have someone else becoming standard bearer for the Sunnis. One more factor is the US election. All parties probably agreed to something predictable and filling the 2 vacant seats (PM + president) rather than deal with the uncertainty of a new US administration.