I’m an outside observer (not American and not into party politics in my own country) but it’s historically unlikely. The US mid-terms have, in regent history, resulted in losses for the incumbent administration’s party. It seems to be a bit of a traditional protest. This can result on a moderation of party political directions, which is a strength of the US system. Most Presidents win a second term but receive a bit of a slap from the electorate in mid terms. Swinging from one party to another through one term Presidents detracts from political stability. The US just seems to tend towards stability and 2 parties without big differences in policy. The mid term slap is, in my opinion, related to the voluntary voting system. If your guy wins the top job, you’re less likely to vote in mid terms.