The head of a cabinet government; the prime minister (often used as an abbreviation for 内閣総理大臣).
内閣の総理は明日、記者会見を開く。
The prime minister of the cabinet will hold a press conference tomorrow.
総理は外交政策の転換を発表した。
The prime minister announced a shift in foreign policy.
支持率低下を受けて、総理は説明責任を果たす必要がある。
Following the drop in approval ratings, the prime minister needs to fulfill his duty to explain (the situation).
A leader or overseer who directs and manages affairs; (original/older) used of overseeing or presiding over tasks—can appear with suru to mean 'to oversee'.
彼は大会の総理として会場やスケジュールを調整した。
He, as the organizer (overseer) of the convention, coordinated the venue and schedule.
業務を総理する立場になってから、細かい管理が求められるようになった。
Since taking a position overseeing operations, he has been required to manage details more closely.
古い文書には『事務を総理す』と書かれており、当時は『取りまとめる』の意味で使われている。
In old documents it is written '事務を総理す', where it was used to mean 'to coordinate/oversee' at that time.