Try some of the following links for verification:
the link you send me says 5 could be the possible answer.
The economic side was to provide greater incentives for people to work because they would get to keep relatively more of what they earned
However since he was a democrat he would not just do it if a tax cut is going to result in rich people paying less taxes..
so he must have done it to win public suporrt from republicans for the civil legislation?