Jamie Dimon, the company’s chief executive, told Reuters that they’re planning how such a scenario would impact markets and clients, as well as the response of rating agencies.

“This is like the third time we’ve had to do this, it is a potentially catastrophic event,” he told the news organization.

Dimon’s remarks come as lawmakers scramble to raise or suspend the debt ceiling before the Treasury Department runs out of money—which Secretary Janet Yellen warned Tuesday could happen in a few weeks.

“We now estimate that Treasury is likely to exhaust its extraordinary measures if Congress has not acted to raise or suspend the debt limit by October 18,” Yellen wrote in a letter to House Speaker Nancy Pelosi. “At that point, we expect Treasury would be left with very limited resources that would be depleted quickly.”

Yellen also advised that Congress’s failure to act quickly on the matter may result in “substantial disruptions to financial markets, as heightened uncertainty can exacerbate volatility and erode investor confidence.”

Democrats in the lower chamber passed a bill to suspend the debt ceiling into December 2022, as well as fund the government through the next two months. But Senate Republicans sank the legislation in a vote on Monday.

Then on Tuesday, Republicans blocked an attempt by Senate Majority Leader Chuck Schumer to use unanimous consent to hold a vote to suspend the federal debt limit at a 51-vote threshold.

Senate Minority Leader Mitch McConnell has vowed the GOP will not provide any votes for raising the debt limit.

One option for Democrats is to address the debt limit through reconciliation, which allows them to bypass the Senate filibuster and pass legislation through a simple majority vote. But Schumer said Tuesday that “going through reconciliation is risky for the country and is a nonstarter.”

“If Republicans continue to stand in the way, they will force the country in default for the first time in history,” Schumer said.

Pelosi told reporters that Democrats are already exploring future debt limit options.

“Right now, we have to raise the debt ceiling,” the speaker said at a news conference.

Dimon told Reuters that the U.S. should “never get this close” to potential default.

“I just think this whole thing is mistaken and one day we should just have a bipartisan bill and get rid of the debt ceiling,” he said. “It’s all politics.”