On the one year anniversary of President Trump's inauguration a friend posted something negative about the President on his Facebook page. A mutual friend who likes Trump posted two comments both related to how well the stock market has done under President Trump. It is of course correct that the market has done very well since Trump was inaugurated and market participants are better off for it.
It is also correct that stock market did better during President Obama's first year by about six percentage points. The current nine year bull market was comprised of eight years under Obama and one year (and counting?) under Trump.
It is again, correct that the stock market has an up year almost 75% of the time which means it goes up most of the time under both parties and both parties have been at the helm when it has gone down. Under Bush 43 the S&P 500 dropped 36%. There have been democrats in the Whitehouse when the market has gone down too.
Based on how long cycles have historically lasted it makes sense to think the next negative market event will occur while the current President is in office. If that happens, will it be his "fault" or will it be effects of something started long before he was president? Whatever the answer it won't matter to you the advisor managing client accounts or to you as a do it yourselfer, it would only matter to policy makers who might need to figure out how to fix things...if they even need fixing.
All this is to say that you should leave your politics out of your investing. While the market is headed higher you should be in and I would say you should take defensive action when the market starts to roll over (goes below its 200 DMA, the two percent rule is invoked, and/or the yield curve inverts) regardless of who is in the oval office.