This is a deceptively important point. There are some who argue that the VP is required by the Electoral Count Act to refer to Congress any slate of purported electors that has been submitted to Congress. Pence took the position, correct in my view, that it is only slates certified by some state authority that can be considered in the Joint Session of Congress that meets to receive and count the votes.

From Politico:

When Mike Pence walked into the Capitol on Jan. 6, 2021, facing a withering pressure campaign by Donald Trump, he’d already made a history-defining decision to rewrite the vice presidential script for publicly counting electoral votes.

But the story of Pence’s revisions hasn’t been clear until now. Pence aides tell POLITICO that he sent a deliberate message to Trump supporters about the reason he was refusing to introduce “alternate” slates of presidential electors, which had become a central part of the former president’s plan to overturn the 2020 election results.

Pence knew that he was about to demolish Trump’s effort to cling to power. But doing so meant contending with an immediate problem: the slates of false electors that the sitting president and his allies had hyped for weeks. Trump allies had coaxed loyalists in five swing states to submit signed certificates falsely claiming they were “duly elected and qualified” members of the Electoral College….

“It was a transparent effort to get in front of any accusations that there was any other slate that could’ve been legally accepted,” Short told POLITICO. “We were trying to be transparent with the American people. We figured there’d be confusion with this.”

Days before Jan. 6, 2021, Short said, Pence took an active role in crafting the specific language he used during the session of Congress that was later disrupted by a pro-Trump mob intent on preventing the election from being finalized….

But Pence added another line to this explanation that the preceding vice presidents did not.

Not only would each certificate he introduced be “regular in form and authentic,” he said at the time, but they would be the ones that “the parliamentarians have advised me is the only certificate of vote from that state, and purports to be a return from the state, and that has annexed to it a certificate from an authority of that state purporting to appoint or ascertain electors.”

It was a mouthful with a purpose. Pence was incorporating the specific legal language of the Electoral Count Act — the 1887 law that, along with the 12th Amendment, governs the counting of electoral votes. The law requires that any electoral votes counted by Congress be submitted by official state authorities, like governors and secretaries of state….

Another source familiar with discussions among the then-vice president and his allies in those days said Pence’s decision to revise the wording had another audience: Members of Congress aligned with Trump who also espoused the view that Pence could introduce alternate electors. Pence, the source said, intended to preempt potential points of order or other procedural challenges those members might have made by laying out his thinking.

Indeed, top Trump allies like Stephen Miller and John Eastman pointed to these alternate electors as a way to keep the former president’s election challenge alive. Eastman built them into his last-ditch strategy to pressure Pence to overturn the election himself….

When Pence refused to entertain the alternate electors during Congress’ session certifying Biden as the next president, Trump supporters encroaching on the Capitol became furious. Within an hour, hundreds had breached the building, with some chanting “hang Mike Pence.”

Amid the chaos, Eastman exchanged tense emails with Jacob. Pence’s counsel accused Eastman, in one remarkably blunt missive, of being “a serpent in the ear of the president of the United States.”