Former Vice President Joe Biden admitted on Sunday night that “everything was on the table,” including Social Security cuts, during bipartisan budget talks in which he participated.

In a one-on-one Democratic presidential debate in Washington, Biden accused Sen. Bernie Sanders (I-Vt.) of airing TV ads that inaccurately claimed Biden had supported cuts to Social Security benefits.

It sparked a prolonged exchange between the two in which Sanders pointed to times that Biden had either voted for or voiced support for cuts to the program.

“You were in the Senate for a few years, time and time again, talking about the necessity ― with pride ― about cutting Social Security, cutting Medicare, cutting veterans programs,” Sanders said.

Biden inaccurately argued that he had never cast votes for legislation that would have cut Social Security.

But he also conceded that “everything was on the table” during deficit-reduction talks he had taken part in, an apparent reference to negotiations with Congress when he was second-in-command in the Obama administration.

“What is true is in terms of the negotiations that were taking place, how to deal with the deficit, everything was on the table,” Biden said. “I did not support any of those cuts in Social Security or in veterans [benefits].”

Sanders, sensing a vulnerable moment, interjected.

“Whoa, whoa, whoa ― ‘everything was on the table’: All right, you’re right, you just said it ― including cuts to Social Security and veterans,” Sanders said.

MANDEL NGAN/Getty Images Even as he confessed to his role in discussions of Social Security cuts, former Vice President Joe Biden inaccurately denied other elements of his record.

Rather than walk back the admission, Biden said it was done in the context of seeking concessions on other Democratic priorities.

“In order to get the kinds of changes we need on other things related,” Biden replied. “But we did not cut it.”

“I know, because people like me helped stopped that,” Sanders answered. “You just contradicted yourself… One minute you said, ‘I was not on the floor [calling for cuts],’ the next minute you say, ‘Well, yes, there was a reason why I was worried about the deficit.’ Maybe it’s a good reason, maybe it’s not. All that I am saying is you were prepared to cut and advocated for the cuts.”

“I did not ― I never voted to cut Social Security,” Biden responded

“Not talking about voting, Joe ― that’s not what I said,” Sanders concluded.

The negotiations Biden mentioned presumably referred to his role in 2011 debt-reduction talks with congressional Republicans in which Social Security cuts were part of a list of changes Democrats were considering in exchange for potential concessions from GOP lawmakers on Democratic priorities like new revenue. Those talks fell apart, but they stand as a testament to Biden’s prominent role in the Obama administration’s ultimately unsuccessful, multi-year quest to strike a fiscal “grand bargain” with Republicans.

In particular, then-President Barack Obama, with Biden at his side, dangled the prospect of a more modest cost-of-living adjustment for Social Security, veterans benefits and other programs in exchange for potential new revenue and cooperation on other items. The resistance of ultra-conservative Republicans helped spike those talks, but Sanders is correct in noting that progressive protests he helped lead generated pressure from the left as well.

SAUL LOEB/Getty Images Biden speaks as then-House Majority Leader Eric Cantor (R-Va.) looks on during a meeting discussing plans to reduce the debt in May 2011. The negotiations never bore fruit.

Meanwhile, Biden’s contention that he has never voted to cut Social Security is simply not true. Throughout the 1980s, 90s and 2000s, Biden, then a senator from Delaware, was part of a prominent faction of Democrats who saw embracing cuts to Social Security as a mark of fiscal seriousness. For example, in 1995 he voted for a narrowly defeated constitutional amendment that would have required a balanced federal budget every year. At the time, liberal policy experts warned that by subjecting Social Security to automatic, across-the-board caps absent budgetary offsets, such an amendment would have risked cutting the benefits issued by the self-funded program.

As a presidential candidate in 2007, Biden said on NBC’s “Meet the Press” that he would “absolutely” consider raising the eligibility age for Social Security or cutting the cost-of-living adjustment.

In the exchange with Sanders on Sunday, Biden also denied that he had ever been supportive of the Bowles-Simpson fiscal commission that the Obama administration convened in 2010 for the express purpose of recommending major cuts to Social Security and Medicare.

“I was not a fan of Bowles-Simpson,” Biden said.

Whether or not Biden was individually a “fan,” he was part of an administration that convened the bipartisan commission and subsequently set out to fulfill its mandate of scaling back the country’s major social insurance programs in the name of debt reduction.

Shortly after the commission completed its business, Biden hired the panel’s staff director, Bruce Reed, as his chief of staff. Some politics watchers interpreted the hiring as a sign that the administration took the commission’s mandate seriously. Reed, who has been at the heart of many of the Democratic Party’s business-friendly policy initiatives over the years, is now a top policy adviser to Biden’s presidential campaign and often travels with him.

As has been the case during so many of the Democratic presidential debates, CNN and Univision’s debate moderators did not step in at any point to note that Biden had spoken inaccurately.

In a follow-up question, CNN’s Dana Bash did ask Sanders to explain whether he could credibly criticize Biden, since he wrote in a 1996 op-ed that he supported “adjustments” to Social Security. “It is clear we will have to make incremental adjustments in Social Security taxes and benefits,” Sanders wrote at the time.

Sanders replied that he was calling for higher, rather than lower, benefits. “Adjustments that I advocated and have advocated for years, is among other things, increasing the cost of living assistance,” he said.

CNN’s Andrew Kaczynski backed Sanders up on Twitter, noting that he had found a Sanders op-ed on Roll Call from 1997 in which Sanders explicitly called for lifting the cap on income taxed for Social Security.

Overall, the exchange was a strong moment for Sanders in a debate where Biden’s experience in the Obama White House appeared to give him the upper hand. Sanders had been hoping to make an issue of Biden’s history of interest in Social Security cuts for some time, but previous debates that included several other candidates who have since exited the presidential race did not allow for such an extended back-and-forth.

In addition to inaccurately denying elements of his record on Social Security, Biden has defended himself by pointing to his current plans to expand Social Security benefits and shore up the program’s finances by lifting the cap on earnings subject to the Social Security tax.

He reiterated that commitment on Sunday. “I have laid out how I will increase Social Security benefits,” he said.

Sanders only decided to hit Biden on Social Security on the airwaves the day after a series of losses to him in the March 3 Super Tuesday round of primaries. The delay in getting on TV with his criticism of Biden was reportedly a sore point among some aides and supporters.