Mitch McConnell, the Republican leader in the Senate, sought to fight his way out of a corner on Friday by releasing an angry letter in which he blamed Democrats for the impasse over the debt ceiling he broke by ending a refusal to co-operate he had said was absolute.

In the letter to Joe Biden, McConnell complained about a speech in which the Democratic majority leader, Chuck Schumer, attacked Republicans for their behaviour.

Lamenting Schumer’s lack of civility – which prompted angry scenes in the Senate – McConnell levelled a string of insults at his opposite number.

“Last night,” the minority leader wrote, late on Friday, “in a bizarre spectacle, Senator Schumer exploded in a rant that was so partisan, angry and corrosive that even Democratic senators were visibly embarrassed by him and for him.

“This tantrum encapsulated and escalated a pattern of angry incompetence from Senator Schumer … this childish behavior only further alienated the Republican members who helped facilitate this short-term patch. It has poisoned the well even further.”

Democrats argue it was McConnell who poisoned the well by refusing to co-operate with raising the debt limit, a step they took repeatedly with Donald Trump in power. Experts say a US default would be catastrophic for the global economy.

McConnell insisted: “In light of Senator Schumer’s hysterics and my grave concerns about the ways that another vast, reckless, partisan spending bill would hurt Americans and help China, I will not be a party to any future effort to mitigate the consequences of Democratic mismanagement.”

McConnell also spoke to Biden, media outlets reported.

The Kentuckian made his move a day after he and 10 other Republicans provided decisive support for a $480bn federal debt limit rise, enough to last two months. Treasury secretary Janet Yellen had said that without such a rise, the US would default on its debts by mid-October.

Some Republicans criticized McConnell for not holding out longer, which they said would have sharpened their contention that a multibillion-dollar package of Biden’s domestic spending priorities, currently making its way through Congress, is wasteful and damaging.

Trump, who remains influential in the party and will stage a rally in Iowa on Saturday, was among those to lambast McConnell for what Lindsey Graham, of South Carolina, called his “complete capitulation”.

In his speech, Schumer lauded Democrats for overcoming a “Republican-manufactured crisis. Despite immense opposition from Leader McConnell and members of his conference, our caucus held together and we have pulled our country back from the cliff’s edge that Republicans tried to push us over”.

As Schumer spoke, Joe Manchin of West Virginia, a key centrist Democrat, was seen to bury his head in his hands. Among Republicans angered by Schumer’s lack of comity and politesse was Mitt Romney of Utah – who had voted against helping raise the debt ceiling.

Romney told reporters: “There’s a time to be graceful and there’s a time to be combative, and that was a time for grace.”

John Thune of South Dakota, a member of Republican leadership who voted with McConnell, said Schumer was “totally out of line”. Of his own confrontation with the New Yorker, he said: “I let him have it.”

But Chris Murphy, a Democrat from Connecticut, tweeted: “Some of my Republican colleagues didn’t like that Schumer called them out … just unreal that they thought they deserved applause for courting economic disaster and then, at the very last minute, delivering the absolute minimum number of votes to avoid it.”

One way for Democrats to raise the debt limit on their own would be to shield debt legislation from filibusters, delays that mean 60 votes are needed in the 50-50 Senate.

Two key Democrats, Manchin and Kyrsten Sinema of Arizona, oppose that, as they have opposed ending the filibuster to protect voting rights or Biden policy priorities. Republicans have said one factor in McConnell providing the two-month debt lifeline was fear that Manchin and Sinema might support ending filibusters on debt legislation.

Democrats accused McConnell of creating a crisis over a debt of around $28tn which covers spending already approved – including around $7tn under Trump.