Final answer:
The word 'nevertheless' is the correct choice for the sentence as it shows a contrast between the president's weakness and the support he receives from most people.
Step-by-step explanation:
The correct word to use in the sentence 'He is a very weak president; ____________. ____________..., most people support him.' is nevertheless. This word suggests a contrast between the first and second part of the sentence, implying that despite his perceived weaknesses, he still has considerable support. The transition word nevertheless fits because it is used to show a concession or agreement that, in spite of the negative aspect mentioned (being a very weak president), there is a surprising or unexpected positive aspect (most people support him).