President Biden is laying the groundwork to blame Senate Minority Leader Mitch McConnell (R-Ky.) if the country defaults on its debt for the first time in U.S. history.

Biden singled out McConnell on Monday for the GOP leader’s insistence that Democrats raise the federal borrowing limit on their own. Continued efforts to block bipartisan legislation on the debt ceiling, the president argued, would make Republicans responsible for the financial consequences.

Speaking to reporters following a speech on the fiscal standoff, Biden said he cannot guarantee that the U.S. will be able to pay its bills past Oct. 18 if GOP senators are unwilling to clear a path to keep the country solvent.

“I cannot believe that will be the end result, because the consequences are so dire,” he said. “But can I guarantee it? If I could, I would. But I can’t.”

Biden’s warning followed a speech in which he excoriated Republicans for closing off every pathway Democrats have used to suspend the federal borrowing limit and accused the GOP of playing a “reckless, dangerous” political game with the U.S. economy.

The U.S. is on track to default on the national debt by Oct. 18, the date at which Treasury Secretary Janet Yellen said the government will run out of the cash and accounting measures necessary to stay solvent. While Republicans voted to raise the debt ceiling three times under former President Trump, they’ve blocked several Democratic attempts to do so.

Senate Republicans last week blocked a House-passed bill to extend government funding and raise the debt limit and later an attempt from Senate Majority Leader Charles Schumer (D-N.Y.) to pass a debt ceiling suspension by unanimous consent. The House passed its own measure to suspend the debt ceiling last week, and Schumer is expected to bring it up for a vote this week.

In Monday’s speech, Biden urged Republicans to clear a path for Democrats to pass that measure if the GOP is unwilling to take responsibility for trillions added to the debt by both parties.

“Democrats are willing to do all the work,” Biden said. “Republicans just have to let us do our jobs.”

“You don't want to help save the country? Get out of the way so you don't destroy it,” he added.

Raising or suspending the debt ceiling does not affect the size of the national debt or future spending. Instead, it allows the Treasury Department to issue new bonds to generate cash and pay off expenses approved over several decades by both parties.

GOP senators have vowed to block any Democratic attempt to raise the debt ceiling unless it comes through the budget reconciliation process, the vehicle for Biden’s multitrillion-dollar social services and climate bill. That process allows for the legislation to pass with a simple majority, meaning Democrats don’t need any GOP support.

In a Monday letter to Biden released shortly before the president’s remarks, McConnell reiterated the GOP’s months-long position.

"Your lieutenants in Congress must understand that you do not want your unified Democratic government to sleepwalk toward an avoidable catastrophe when they have had nearly three months' notice to do their job," McConnell wrote.

"Republicans' position is simple. We have no list of demands. For two and a half months, we have simply warned that since your party wishes to govern alone, it must handle the debt limit alone as well.”

If Congress does not act to raise the debt ceiling after the so-called X date, the U.S. could miss debt payments for the first time in its history and unleash a potential economic and financial catastrophe.

The U.S. could find itself unable to fund basic federal entitlements and services — including Social Security checks and salaries for military and federal personnel — as the recovery from the coronavirus recession faces new threats. Interest rates within the U.S. would likely skyrocket and global financial markets could seize as trillions of dollars of Treasury bonds become irredeemable.

Democrats and Republicans have faced off over the federal debt limit for decades and have never allowed the U.S. to default due to the dire implications. But the GOP’s unwillingness to even consider voting for a debt limit increase has alarmed budget experts and Capitol Hill veterans involved in past standoffs.

“I've dealt with the debt limit many times before when I was up there. For some reason, this one has me more scared than any other,” said Bill Hoagland, senior vice president at the Bipartisan Policy Center, who spent almost three decades as a high-ranking Senate GOP budget aide.

“When this debt limit issue has come up, there's been some demands from the party out of control,” he said. “What bothers me about [McConnell’s] letter is he says, ‘We have no list of demands.’ This is fundamentally different than all those previous standoffs.”

Hoagland added that he was also concerned about Democrats’ refusal to consider raising the debt ceiling through the budget reconciliation process, which could take up to two weeks.

Schumer and Speaker Nancy Pelosi (D-Calif.) each ruled out using the reconciliation process to raise the debt limit last week. Both leaders insisted that the process is too complicated to address such an urgent issue, even though reconciliation rules specifically allow for raising the debt limit to a defined level.

While Biden did not close the door on raising the debt limit through reconciliation on Monday, he also expressed concerns about going down that route. Raising the debt limit through budget reconciliation could involve dozens of votes on amendments that could create myriad new problems, he argued.

“It's an incredibly complicated, cumbersome process, and there's a very simple process sitting at the desk in the United States Senate,” Biden said, referring to the House-passed bill.

Hoagland said that if Democrats begin the process soon, they could still have ample time to raise the debt limit with the reconciliation process through a separate vote from their eventual social services and climate package. Even so, that would require McConnell to keep his conference from trying to delay the process, and several conservative Republicans have vowed to fight a debt ceiling hike tooth and nail.

For that reason, Hoagland explained, Republicans should not filibuster a standard bill to raise the debt limit and allow Democrats to keep the country solvent without a single GOP vote — just as McConnell demanded.

“McConnell has won,” Hoagland said. “With all due respect to the minority leader, you're not being internally consistent. All you said was, ‘All we want is 51 votes.’ Then don't set up a hurdle of 60 votes.”

Updated at 5:03 p.m.