History. 4 of 8. All four close results were losses for the candidate who beat the leaders' choice.
Hunch. The only recent poll in the reports, Marist in late September, has a seven-point gap, which is wider than the five-point line.
The close-race market resolves on the same official Michigan results: YES if the winner's share of all votes is less than 5.0 points above the runner-up's, whoever wins, and NO at 5.0 points or more. If the state site cannot be opened, matching figures in BBC News and The Guardian reports settle it.
We looked for cases where a candidate won a party primary for the US Senate against the person the party's leaders backed, and then faced the general election. We found eight since 2010, seven of them Republicans. In two, the seat was open and it belonged to the candidate's own party, as in Michigan now.