WASHINGTON — Some Senate Democrats are circulating a letter urging President Joe Biden to prepare to invoke the 14th Amendment to raise the debt ceiling and avoid default on his own, without an act of Congress.

The pop-up letter, which is still in the works, is a sign of growing dissatisfaction with some aspects of the legislative negotiations, such as Republican demands to impose stricter work requirements to receive federal benefits. The letter is addressed by Sen. Tina Smith, D-Minn., as well as Sens. Elizabeth Warren, D-Mass., Jeff Merkley, D-Ore., Ed Markey, D-Mass., and Bernie Sanders, I -Vermont. .

«We write to urgently request that you prepare to exercise your authority under the 14th Amendment to the Constitution, which clearly states: ‘the validity of the public debt of the United States…shall not be questioned,'» the senators write in the draft of the letter, obtained by NBC News. «Using this authority would allow the United States to continue paying its bills on time, without delay, avoiding a global economic catastrophe.»

«While we cannot default on our debt, we also cannot allow the destructive Republican budget to be implemented,» they continue.

The draft letter, which is still being circulated for signatures, comes 15 days before the June 1 deadline set by the Treasury Department for Congress to act or risk missing the debt limit.

Sanders said in an interview Wednesday: «The message is that, at a time of massive income and wealth inequality,» Congress cannot «balance the budget on the backs of children, the elderly, and working families and force children to go hungry.

“I mean it’s crazy. Unacceptable. There is a choice: it’s the 14th Amendment, it was put into the Constitution for a good reason,» Sanders said. «The president should implement it.»

On Tuesday, Biden met with President Kevin McCarthy and other congressional leaders, who later offered signs of hope about the negotiations. But McCarthy maintained that they are still «far apart.»

In the letter, which was the first reported Per the Washington Post, Democrats say the GOP’s unwillingness to raise taxes on big, wealthy corporations makes it «seemingly impossible to enact a bipartisan budget deal right now.»

McCarthy flatly dismissed the idea of ​​tax increases for top earners Wednesday at a news conference.

Some experts believe the debt ceiling statute is unconstitutional and cannot prohibit the US from borrowing to pay its debts. But the Biden administration and its predecessors have been reluctant to invoke the 14th Amendment. The Obama administration investigated it, but its Justice Department never made its opinion public on the matter. Some officials were concerned that if such a move were to be challenged in court, it could undermine the full faith and credit of the US.

Biden recently said that he has been «considering» the 14th Amendment, but concluded that it would not resolve the current impasse as it «would have to be litigated.» But the White House Office of Legal Counsel is continuing to study the matter, according to a source familiar with the talks, for possible unilateral use in the future.

Sen. Chris Murphy, D-Conn., expressed skepticism Sunday on NBC’s «Meet The Press» when asked whether Biden should use the 14th Amendment to keep paying the bills.

“I don’t want to give Joe Biden advice, but I think we need to do our job,” Murphy said. «I think it’s a precedent to just absolve Congress of being adults.»

Liz Brown-Kaiser and Monica Alba contributed.