Debt ceiling timeline: When are Medicaid, Social Security and other payments in jeopardy

Unless Washington reaches a deal on the debt ceiling, government payments millions of Americans rely on each month could be in jeopardy in little more than a week.

While the deadline politics play out in Washington, the uncertain timeline of exactly what happens next -- both with those payments and to people's bank accounts -- is only adding to growing anxiety.

Treasury Secretary Janet Yellen maintains the nation could be unable to pay all of its bills in early June, possibly as early as June 1, though the exact date remains unclear.

That means billions of dollars scheduled for programs such as Social Security, Medicare and Medicaid, as well as military salaries and veterans benefits, are at risk of going unpaid or being delayed if no agreement is reached.

President Joe Biden and House Speaker Kevin McCarthy have been adamant the U.S. won't default, but still remained "far apart" on a solution on Wednesday.

What would happen if they don't is uncharted territory: The nation has never defaulted on its debt.

"Right now, we have to remain optimistic that a deal is going to be struck," Rachel Snyderman, the senior associate director of economic policy at the Bipartisan Policy Center, told ABC News.

"But this goes to show that there is a significant cost to brinkmanship over the debt limit, and the confusion and the concern these episodes inflict is is not helpful to American taxpayers who don't have the luxury of choosing which bills they get to pay and don't at the end of the month," Snyderman said.

The Bipartisan Policy Center, a Washington think tank tracking federal cash flows, recently estimated a heightened risk for default between June 2 and June 13. If the Treasury can continue financing the government through June 15, the center and other analysts believe expected quarterly tax receipts will provide the government more time before default.

Payments at risk from June 1 to June 15

A major hurdle: Some $100 billion in payments are scheduled to go out June 1 and June 2, according to the think tank.

"We shouldn’t even be talking about this situation," Biden said earlier this month as he warned such payments were at risk if a default occured.

The heads of the U.S. military services said during a Council of Foreign Relations panel this week their operations would be affected if the debt ceiling is not raised.

"We've got to make sure that our troops get paid," said Gen. James McConville, the Army chief of staff.

McConville added, "You know, probably one of the best quotes I've ever heard was from a young specialist's wife in the 101st Airborne Division. [During one of the last government shutdowns] when the government [said there might not be] paychecks, and they said said [troops and their families] will get paid retroactively -- what she said is, 'My kids can't eat retroactively'."

Emotions are running high.

Illinois Democratic Rep. Jan Schakowsky, during a news conference with the House Progressive Caucus Wednesday, passionately relayed concerns she said she heard from one of her constituents, "Janet," who she said suffered from chronic mental illness and fears she won't be able to pay for rent, food or medications.

"There are a million Janets all over the world who are sitting at home, if they understand what is going on, and watching to see what the Republicans are going to try to do to them," Schakowsky said.

Possible contingencies?

There is no roadmap for a default, but some have said the Treasury Department could prioritize which payments to make and which to ignore.

The Republican-led House Ways and Means Committee earlier this year advanced a bill that would require the Treasury to first pay all principal and interest on the national debt, then all Social Security and Medicare benefits.

But officials, including the Treasury secretary, have expressed skepticism about whether such prioritization is possible or legal.

"I would say that our payment systems have been constructed in order to pay our bills, not to decide which bills to pay and which bills not to pay," Yellen said Wednesday during a Wall Street Journal summit. "And so as a general matter, prioritization is not really something that's operationally feasible."

Asked whether Medicaid or Social Security checks would be prioritized after the "x-date" -- or date of default -- White House press secretary Karine Jean-Pierre emphasized prioritization is "not the plan."

"It is a recipe for economic catastrophe," she said on Wednesday.

Another potential option could be for the Treasury to delay all expenditures until there was enough revenue to cover an entire day's worth of payments.

Chris Campbell, chief policy strategist at the financial services firm Kroll and a former assistant Treasury secretary, previously told ABC News that "in the extremely unlikely event that [default] occurs, I'm certain that the Treasury Secretary would have a series of options at her disposal to be able to work through the challenges should that occur."

But Yellen on Wednesday reiterated the Treasury is "committed to not having missed payments and raising the debt ceiling."

"We are not involved in planning for what happens if there is a default," she said.

-ABC News' Luis Martinez and Chris Boccia contributed to this report.