If you look back at the recent history of the Fed, they have consistently acted to undermine republican presidents. It happened with Bush 41, allowing Clinton to run against the "Bush recession", even though the economy was in fact recovering. It happened at the end of Bush 43's second term, when the idiot Bernanke raised rates precipitously after allowing a housing bubble to inflate on his watch. The Fed then graciously undertook a zero interest rate policy for the entire eight years of Obama's disastrous presidency, allowing him to run up monstrous debt and brag about an economy that was in fact suffering from his policy mistakes. Barely a year after Trump took office the Fed was back to raising rates, even though inflation is nonexistent.
The Fed's current obsession with raising rates happens to directly undermine Trump's two biggest economic success stories. One is raising the incomes of his working class base. Obama's economy made Wall Street and Silicon Valley execs rich, and of course they showered him with money in response. Wage earners were a different story. They saw their jobs sent overseas or replaced with cheap immigrants. The Fed paradoxically is fixated on wage costs as justification for raising rates. So to the extent Trump helps the working class, the Fed tries to take it away. This shows some real chutzpah since they were so desperate to bail out the bankers, whatever the cost.
Trump's other economic success story, forcing the Chinese to bend the knee on trade, is also directly undermined by the Fed. As rates go up, so does the dollar, and the effect of Trump's tariffs is negated. In effect, we are manipulating the Chinese's currency for them. Or to put it another way, one part of the government has its foot on the accelerator while the other is on the brakes.
The stock market is scared and rightly so. The Fed has a terrible record and has repeatedly made the exact same policy mistake that seems on the launching pad now. By using lagging data like employment stats, they tighten for too long and create a recession. In this case, that recession should coincide nicely with the 2020 elections. Accident? Bad luck? Once or twice, maybe. When it happens election after election, you begin to wonder if the "career professionals" at the Fed are as politicized as their counterparts at the DOJ, IRS and FBI.