Here’s a question that comes up every election cycle, and you don’t even need to read all 198 pages of the FEC congressional guide to get the answer.
Jo Holt, head of the Pima County Democratic Party, has filed a complaint with the Federal Election Commission, aruging that it is “inconceivable” that McSally has not spent more than $5,000 in seeking the Senate seat. The Democrats maintain that McSally “apparently” hired a polling firm to gauge her name recognition for a statewide race for the Senate.
Here’s the answer contained in the first three sentences of the FEC Candidate Guide:
Before deciding to campaign for federal office, an individual may want to “test the waters,” that is, explore the feasibility of becoming a candidate. For example, an individual may want to conduct polls or travel around the state or district to see if there is sufficient support for his or her candidacy. An individual who merely tests the waters, but does not campaign for office, does not have to register or report to the FEC.
https://www.fec.gov/resources/cms-content/documents/candgui.pdf