Quid pro quo
Quid pro quo (Latin , "Something for Something") is a term referring to a person providing or promising something, in exchange for an expected future benefit in return.
It is most commonly used in the context of requests on government officials. Not all such actions are per se illegal: people make donations to candidates and expect that, in return, the candidates will support their side of an issue (e.g. if Planned Parenthood donates to a candidate, it expects the candidate to support abortion on demand; similarly, if the United States Chamber of Commerce donates to a candidate, it expects the candidate to support expanded trade).
However, most such transactions are considered bribes and, thus illegal: the Rod Blagojevich seat-selling scandal was a "quid pro quo" that resulted in a lengthy prison sentence for the (pro-abortion) former governor of Illinois.
Democrats accused President Donald Trump of engaging in a "quid pro quo" whereby the U.S. would send aid to Ukraine only if it investigated the corruption related to Joe Biden when he was Vice President and his son Hunter was being paid $50,000 a month by a Ukrainian natural gas company despite Hunter's lack of relevant experience. This alleged quid pro quo was the basis for a Democrat impeachment effort in 2019.