Ahead of the White House sitdown between President Joe Biden and top congressional leadership Tuesday about the country’s borrowing power, the Treasury Department’s No. 2 official issued a stark warning about the consequences of the U.S. defaulting on its debt if no deal is reached.

“I can’t overestimate the significant consequences a default would have on the U.S. economy,” Deputy Treasury Secretary Wally Adeyemo told Spectrum News in an exclusive interview. “It would be larger than what happened when Lehman Brothers failed for the U.S. economy.”

Adeyemo worked in the Obama administration’s Treasury Department in the immediate aftermath of the 2008 collapse of the financial services firm Lehman Brothers, the largest bankruptcy in U.S. history, which helped deepen the 2008 financial crisis into the worst recession since the Great Depression.

His rhetoric is in line with how the White House has been framing the debate. The White House’s Council of Economic Advisers projected a protracted default could lead to the loss of 8.3 million jobs and a 5% increase in unemployment. Even if the debt ceiling negotiations were to go down to the wire, hundreds of thousands of jobs could be lost, Biden administration economists said.

“Outside forecasters say that we would lose millions of jobs in the United States if the United States defaulted on its debt, and I think that is an underestimation of the consequences for the U.S. economy,” Adeyemo said. “It would mean that small business owners would have the inability to get not only loans, but their customers would largely dry up.”

House Republicans are at an impasse with Biden and congressional Democrats, who want what is known as a “clean” debt limit increase -- raising the debt ceiling without conditions. The House GOP last month passed a bill that would raise the debt ceiling in exchange for federal spending cuts, something Democrats have said they will only consider after the debt ceiling is raised.

The view from Biden and his allies is that the consequences of failed debt ceiling negotiations is far too risky to the global economy, while Republicans argue the national debt of roughly $31 trillion has ballooned out of control and needs to be reined in.

“We should also have a conversation about what we do in terms of our budget going forward, we just shouldn't have that conversation about the budget in the context of threatening not to pay Social Security recipients not to pay members of our police forces,” Adeyemo said. “The president's called for reducing our deficit by $3 trillion over the next 10 years, and he's happy to have a conversation with [Speaker of the House Kevin McCarthy] and members of Congress about how we do that.”

With Treasury Secretary Janet Yellen projecting a debt default day as early as June 1, time is running out for the United States’ elected leaders, who have stood firm on their respective positions for months now.

Some advocates and experts have pushed the Biden administration to circumvent Congress with untested theories, including by minting a $1 trillion coin to pay the nation’s bills or by simply ignoring the debt limit by way of the 14th Amendment, which states, in part “the validity of the public debt of the United States… shall not be questioned.”

Adeyemo, as Yellen has previously, dismissed alternative pathways, arguing Congress lifting the debt limit, as they have more than 100 times in the last century, is the only path forward.

“It's the only way to provide certainty to financial markets, but also to the American people, that our bills will be paid, and that if you're a Social Security recipient, you will get your check on time. That if you are a troop defending our country somewhere abroad, or you're in this country, that you're going to get paid,” Adeyemo said. “The consequences of default would be severe. And we have the ability to prevent that by Congress acting.”