The Treasury Department warned congressional leaders on Monday that the government could run out of money to pay its bills as soon as June 1, prompting President Joe Biden to call a meeting amid a standoff between House Republicans and the White House that threatens to send the nation into an unprecedented default.

“After reviewing recent federal tax receipts, our best estimate is that we will be unable to continue to satisfy all of the government’s obligations by early June, and potentially as early as June 1, if Congress does not raise or suspend the debt limit before that time,” Treasury Secretary Janet Yellen wrote in a letter to congressional leaders on Monday.

Yellen noted that the exact date that the government will be unable to pay its bills, known as the “x date,” is “impossible to predict with certainty.” Nevertheless the new estimate, just one month away, comes earlier than she had previously projected, and leaves Congress with limited time to act.

Since the government reached the debt limit in January, the Treasury Department has been employing “extraordinary measures” to extend the date that it’s expected to run out of money. On Monday, Yellen told congressional leaders that the agency would suspend the issuance of certain Treasury securities issued to states and municipalities that “count against the debt limit,” though she noted the move will “deprive state and local governments of an important tool to manage their finances.”

Even with additional measures, Yellen warned that Congress must act quickly on the debt limit.

“We have learned from past debt limit impasses that waiting until the last minute to suspend or

increase the debt limit can cause serious harm to business and consumer confidence, raise short-term borrowing costs for taxpayers, and negatively impact the credit rating of the United States,” she wrote. “If Congress fails to increase the debt limit, it would cause severe hardship to American families, harm our global leadership position, and raise questions about our ability to defend our national security interests.”

The nonpartisan Congressional Budget Office echoed the Treasury Department’s estimate on Monday, projecting that “there is a significantly greater risk that the Treasury will run out of funds in early June,” after previously forecasting that they would run out between July and September.

The new estimate comes after House Republicans last week approved legislation that would raise the debt limit while slashing government spending, some of which is tied to President Joe Biden’s legislative achievements. The bill is dead on arrival in the Senate, and Biden has already pledged to veto it, calling for a clean debt-limit hike, rather than one tied to spending cuts.

But with the legislation’s passage, House Speaker Kevin McCarthy, who has insisted that raising the debt ceiling without addressing “reckless” government spending would be irresponsible, gained a key victory – putting pressure on Biden to come to the negotiating table.

Biden called McCarthy on Monday afternoon to invite the speaker to meet on May 9, the White House said. House Minority Leader Hakeem Jeffries, Senate Majority Leader Chuck Schumer and Senate Minority Leader Mitch McConnell will also attend the meeting.