What was President Zachary Taylor's top priority as president? preserving the Union ensuring the recapture of runaway slaves expanding slavery

Answer: Preserving the union.

Explanation: A serious crisis had just eructed on account of slavery - the immediate consequence of the war waged with Mexico during the presidency of Polk - that he would no longer peacefully remit. Frojm now on, the crisis about the territorial limits of slavery would be inherited from one president to another during the next decade, it would take the life of the second system of the American parties, in addition to hundreds of slaves and activists favorable or opposed to slavery, and would end up leading to the civil war from 1861 to 1865, without any agreement, pact or commitment could avoid it.