President Joe Biden campaigned on protecting Social Security and has slammed what he calls Republican efforts to gut the program through sunsetting, increasing the retirement age and reducing benefits. But the president has nearly a half-century of history dating to at least 1975 of voting or advocating for many of the same attacks on Social Security that he now warns could come from a Republican takeover — and both his historical record and current policies will affect today’s younger generations as they age into the program.