You'll see that the tax rate on those individuals from the highest tax bracket has been dropping precipitously since the end of WWII, regardless of which party held the white house. In fact, the rates began to fall under Kennedy, a Democrat, and continued through Johnson, another Democrat. The tax rate held steady through Nixon, Ford, and Carter, before tumbling further under Reagan. The tax rate bottomed out in 1989, under Bush I, at 28%- less than a third of its modern peak of 94%, under Truman. Bush then raised taxes from their absurd low, and they have been bouncing around the 30s every since. So from this graph it seems pretty clear: Keeping taxes low for the wealthy has been a bipartisan effort for the last sixty years.
The income tax rate for individuals in the lowest tax bracket dropped to 14% under Johnson, and has done pretty much nothing ever since. Lesson: if you are poor, which party holds the white house makes no difference to your tax rate.
Here I plot the Federal deficit in billions of dollars (adjusted for inflation), over time. Again, the years in which the Republicans held the white house are shaded gray. What do we find? The deficit plunges deeper and deeper every time the Republicans take the white house. Johnson, Carter, and Clinton, on the other hand, all turned around large deficits inherited from their Republican predecessors. Clinton's accomplishments are most impressive, but Carter and Johnson had their fiscal victories as well. Contrast these episodes with deficit spending of Eisenhower, Nixon, Reagan, Bush I, and Bush II. This graph should give fiscally conservative Republicans pause.