New York Times:  When Tax Cuts Were a Tough Sell, by Bruce Bartlett:

Fifty years ago this week, on Jan. 24, 1963, John F. Kennedy sent a special message to Congress
on tax reduction and tax reform. Enacted the following year by Lyndon
B. Johnson, the legislation cut the top federal income tax rate to 70% from 91% and the bottom rate to 14% from 20%. Ironically, it later became the template for Republican tax
policy.

Those who don’t know the history probably assume that the tax cut was a
slam-dunk for Kennedy, something that was overwhelmingly popular. In
fact, a big tax cut was highly controversial because at that time
Republicans actually cared about the deficit and recognized that tax
cuts would increase it. This view was shared by the large bloc of
conservative Southern Democrats then in Congress and the general public
as well. …

Kennedy’s tax plan was exactly what Republicans today recommend, but
they opposed it strenuously at the time. The Republican members of the
Ways and Means Committee unanimously opposed it, saying, “It is morally and fiscally wrong, and will do irreparable damage to the Republic.”

When the tax cut came up for a final vote
in the House of Representatives on Sept. 25, 1963, only 48 Republicans
supported it; 126 voted against it. Nevertheless, it passed by a vote of
271 to 155. … It is probably only because of Kennedy’s assassination in November 1963
and the strenuous efforts of Johnson, who had led the conservative
coalition in the 1950s as Senate majority leader, that the tax cut
passed the Senate. Even so, 11 Democrats and 10 Republicans voted against its final passage on Feb. 7, 1964.