Trump-Biden transition updates: At least 20 arrested, 1 stabbed at DC protests

British Prime Minister Boris Johnson joins a growing list of foreign heads of state to congratulate Biden despite Trump's continued refusal to concede.

Johnson tweeted Tuesday afternoon that the two discussed their "shared priorities – from tackling climate change, to promoting democracy, and building back better from the coronavirus pandemic."

A Downing Street spokesperson told pool reporters Johnson and Biden discussed the countries' partnership through NATO -- an alliance Trump has repeatedly slammed.

Johnson also invited Biden to attend the COP26 climate change summit that the United Kingdom is hosting in Glasgow next year and said he also looks forward to seeing him when the UK hosts the G7 Summit in 2021, according to the spokesperson.

Democrats and Republicans, as expected, are split over whether Attorney General William Barr’s memo to U.S. attorneys -- in which he authorized them to probe widespread voter fraud, despite no evidence of its existence having surfaced -- was appropriate to send. 

“Attorney General Barr has unfortunately done great harm to the reputation of that office, and to the Department of Justice,” said Sen. Dick Durbin, D-Ill., calling his action “unprecedented and unforgiving.”

“The notion that the Department of Justice is going to interfere in the election process before the president leaves, to me, is just inexcusable. It's not -- it's no surprise,” he added. 

House Judiciary Chairman Jerry Nadler, D-N.Y., also criticized Barr in a written statement Tuesday, arguing the decision “speaks to Barr’s dangerous and irresponsible impulse to pander to the President’s worst instincts.”

Sen. Ted Kennedy, R-La., a close ally to Trump, meanwhile, called it “perfectly appropriate,” adding the election isn’t over until the Trump team has had its cases heard.

“Tens of millions of Americans believe, whether you agree with them or not, that we need to send Big Bird to some of these states to teach them how to count,” Kennedy said. “For the integrity of the electoral process, and the system that we have chosen to effectuate our democracy, we have got to allow our courts to hear these allegations of voting irregularities by the president and anyone else who wants to bring them forward.”

-ABC News' Allison Pecorin and John Parkinson

Bob Bauer, the Biden team's attorney tasked with leading its legal response to the election, slammed Attorney General William Barr after Barr, in a memo Monday night, authorized U.S. attorneys to pursue allegations of voter fraud, despite no evidence surfacing thus far of any widespread voter fraud in the 2020 election. 

“It is deeply unfortunate that Attorney General Barr chose to issue a memorandum that will only fuel the ‘specious, speculative, fanciful or far-fetched claims’ he professes to guard against,” Bauer said. “Those are the very kind of claims that the president and his lawyers are making unsuccessfully every day, as their lawsuits are laughed out of one court after another.”

“But, in the end, American democracy is stronger than any clumsy and cynical partisan political scheme,” Bauer added. 

In the memo Barr sent Monday evening, he authorized U.S. attorneys to "pursue substantial allegations of voting and vote tabulation irregularities” and said such inquiries "may be conducted if there are clear and apparently-credible allegations of irregularities that, if true, could potentially impact the outcome of a federal election in an individual State." 

The action comes days after ABC News and other outlets characterized Biden as the president-elect and raises the prospect that Trump is seeking to use the Justice Department to try to challenge the election.

-ABC News' Mary Bruce and Alexander Mallin

In a public letter to General Services Administration's (GSA) Emily Murphy released Monday night, three House Democrats, all of whom chair committees, sought an explanation for what they deemed the GSA’s “stunning refusal to follow the law and acknowledge President-elect Joe Biden’s decisive victory.”

“By failing to ascertain Joe Biden and Kamala Harris’ resounding victory, you are undermining the urgent need for a prompt and effective transition of power in the midst of a global pandemic that must be focused on the safety and well-being of our citizens,” wrote Reps. Bill Pascrell Jr., D-N.J., Gerry Connolly, D-Va., and Dina Titus, D-Nev.

Traditionally, the GSA recognizes a candidate that has clearly won the election, allowing the winning ticket's team to access a variety of resources available to aid the transition process, including $6.3 million in Congressionally-appropriated funds -- but so far, Murphy, who was appointed by Trump in 2017, has made no such determination.

The Biden transition team also believes that the time has come for the GSA to "promptly ascertain Joe Biden and Kamala Harris as president-elect and vice president-elect," adding, in a call with reporters Monday night, that if the GSA refuses to do so, a variety of options are on the table, including the possibility of legal action.