NO. The story is much older than that.
Most Catholics are 19th & 20th century immigrants, except for a minority found in the South. When they came into the country, their votes were cultivated by the Democrat party, particularly in the Northeastern part of the country. To this day, this is why they are stronger there than in the west. Catholics usually voted Democrat for this reason. It was expected. There were alliances between Catholic figures and the Democrat party and Democrats did things for Catholics in those days.
However, as Catholics moved into the mainstream in the 60s and out of the Catholic ghettos of the past, they became more like the mainstream, and felt more free to analyze questions for themselves. This is because they were more likely to have non-Catholics as their colleagues and live in non-Catholic neighborhoods with non-Catholic expectations. The trauma of Vatican II, no matter how you view that theologically, contributed to this effect also because it loosened the Catholic community. You no longer saw other Catholics during the week, usually. Also, the Democrat party moved away from the Church and decided that we’d vote for them forever, even if they treated us like ****, because we’d been so reliable in the past. They still take us for granted.
A lot of time has passed since most Catholics have been immigrants. The personal bonds and expectations of fairness no longer exist. Catholics are now much more mainstream and act like it. In fact, now, Catholics are much more like the general population than they are like each other. This is why there is no longer an identifiable Catholic bloc in American politics. If you poll Catholics, our demographics are very much like the demographics of the general population. Catholic identity is a minor factor.
BTW, the Reagan presidency was crucial for this too. He was a very powerful figure in the breakup of the Catholic vote. Catholics learned that it was perfectly all right to vote for a non-Democrat and it could be beneficial to Catholics to do so. That’s still the case. In fact, it’s even more the case now, if you want to know the truth. The Democrats are simultaneously persecuting us and taking us for granted. Many Catholics are aware of this now.