Too much credit or blame goes to the President for economic outcomes. The President in our system of governance, unlike kings and dictators, must elicit from Congress support and approval for any initiative. One would expect that the performance of Presidents who presided with a united Congress to exceed those who presided over a divided Congress. And even then, one would have to correctly assign the lag effect between enactment of legislation and outcomes. For instance, concluding that the outcomes of the Reagan economic initiatives occurred during the Clinton years is not without merit.
The Presidents who had a unified Congress did not have to negotiate as much or at all to have their initiatives enacted into law while those Presidents who had a divided Congress did have to negotiate and had their initiatives enacted either in a watered down version or with additional legislation opposed to their principles. Reagan never had a unified Congress. Neither did G.W.H. Bush. Regan had to negotiate with Tip O’Neil. To get an increase in military spending necessary to end the cold war with Russian communism, Regan had to give O’Neil offsetting increases in domestic spending adding to the national debt.
Interestingly, the Presidents in modern times who have had a unified Congress are the Democrats – Carter, Clinton and Obama (8 years).
After the 9-11 attack, G.W. Bush had 4 years of a unified Congress and in 2016, with the economy stalled, Trump now has a unified Congress for 2 years.
When Democrats control, one seldom hears about a “maverick” Democrat blocking Presidential spending increase initiatives but when the Republicans control “mavericks” abound. Does the “tax and spend” door hanger that Republicans pin on the Democrats have merit? It seems true for at least the “spend” part. And even more true if rephrased as "spend and borrow."