The 1981 op-ed ran with a searing headline, “Congress is Subsidizing Deterioration of Family,” and made a jarring argument: Couples with higher income shouldn’t get tax credits for child care because, if they can afford it, one parent should stay home.

The author was Joe Biden, then a senator from Delaware. On Wednesday, Biden found himself under attack from Sen. Kirsten Gillibrand (D-N.Y.), who argued during the Democratic presidential debate in Detroit that the column — along with Biden’s Senate vote against the measure — showed he opposed helping mothers to join the workforce.

“You said women working outside of the home would lead to the deterioration of family,” said Gillibrand, while highlighting her own experience as a working mother. “My grandmother worked outside the home. My mother worked outside the home.”

Biden hit back that he never opposed working mothers or subsidizing parents with lower incomes.

“I wanted the child care to go to people making less than $100,000,” he said. “As a single father who in fact raised three children for five years by myself, I have some idea what it costs.”

The fiery exchange came on a night where the other candidates assailed Biden, who has led most polls in the early going, and suggested that Gillibrand, who has struggled to break through so far, saw an opportunity to distinguish herself from the former vice president on women’s rights.

The fact that she turned to a 38-year-old column and Senate vote to do so again illustrated how Biden is potentially vulnerable on a host of decades-old issues — from criminal justice reform to racial equity to immigration — where his record has now diverged from many Democrats.

In the case of child-care tax credits, though, Biden was an outlier even at the time.

His 1981 column came as the Senate was considering expanding a child-care tax credit, as HuffPost reported on Friday. Biden, then 38, brought a unique perspective because his wife and 1-year-old daughter had been killed in a car accident nine years earlier, leaving him alone to raise their other children just as he entered the Senate.

Part of Biden’s opposition to the proposed expansion was economic. On the Senate floor, he said it was wrong to make “folks in low-paying jobs” pay for credits going to parents making more than $30,000, the equivalent of nearly $90,000 today (though some critics argued that would also have excluded middle-class families from the credits).

But he also framed his argument in terms of “individual responsibility.” The credit would encourage couples with more money to seek child care, he said, just so both parents could work and afford “a larger home, a patio, a swimming pool.” In the op-ed, he termed day-care centers “monuments to our growing unwillingness to accept personal responsibility.”

“I do not believe the federal government should be party to a system which encourages couples to place their children in day-care centers in order to acquire material possessions that go far beyond any basic necessities,” he wrote.

Despite Gillibrand’s claims on Wednesday, Biden never explicitly said that working women, in particular, were leading to the “deterioration of family.” In fact, as HuffPost noted, he took some pains to argue otherwise.

“I do not care whether in a modern marriage you want the man or the woman to take that responsibility,” he said, per an Indianapolis News report in July 1981, referring to the job of staying home with a child. “That has to be resolved by each couple individually.”

But, as HuffPost reported, women disproportionately bear the responsibility for child care. If one parent stays home, statistically speaking it’s much more likely to be the mother. Even if Biden’s argument didn’t explicitly target women, the effects of his policy likely would have.

Regardless, Biden’s arguments did not strike a chord in the Senate. In the end, he was the sole dissenter in a 94-1 vote in favor of the expanded tax credit. Biden’s efforts to add an amendment eliminating the credit for wealthier couples, which would have left an exception for single parents of all incomes, also failed.

On Wednesday, Biden pointed to his support in later years for a variety of child-care tax credits, as well as his backing for many women’s rights bills. He also said that as president, he would support “making sure that every single solitary person needing child care gets an $8,000 tax credit.”

Still, Gillibrand wasn’t satisfied. Biden’s argument in 1981, she said, “causes concern for me because we know that America’s women are working. Four out of 10 moms have to work. They are the primary or sole wage earners. They actually have to put food on the table.”

As moderators signaled they had to move on to the next question, she again demanded to know whether he believed that women working outside the home would lead to the “deterioration of family.”

“I never believed that,” Biden said.