Democrats, still bitter about losing the presidential election, blame the loss on Federal Bureau of Investigation (FBI) director James Comey - and some are calling for him to resign and be investigated.
The calls have grown in the wake of recent reports that the FBI had known about Russia's attempts to influence the election, but allegedly failed to respond adequately.
Critics contrast this with the intensity with which Mr Comey had probed Democratic presidential candidate Hillary Clinton's use of a private e-mail server.
"Swing-state voters made their decisions in the final days breaking against me because of the FBI letter from director Comey," Mrs Clinton told a group of donors in Manhattan last Thursday.
On Dec 11, statistics guru Nate Silver tweeted that Mr Comey "had a large, measurable impact".
"I'll put it like this: Clinton would almost certainly be president-elect if the election had been held on Oct 27 (the day before Mr Comey's letter)," he tweeted.
In The Washington Post last Thursday, Mr John Podesta, chairman of Mrs Clinton's campaign, wrote: "Congress should more vigorously exercise its oversight to determine why the FBI responded overzealously in the Clinton case and insufficiently in the Russian case."
His call echoed that of senior Democrat Harry Reid, who told broadcaster MSNBC that Mr Comey "had let the country down for partisan purposes" and called for a probe.
Asked if Mr Comey should resign, Mr Reid, the retiring Senate Minority Leader, said: "Of course. Yes. But he won't. He's got a term there and I'm sure he's got the new administration... They should like him, he helped them get elected."
Mr Comey has been accused of influencing the outcome by sending a letter to some members of Congress just days before the election, informing them that the FBI had found e-mails pertinent to the probe into Mrs Clinton in the computer of former Congressman Anthony Weiner, the estranged husband of top Clinton aide Huma Abedin.
This was leaked to the media and gave her rival Donald Trump a chance to go on the offensive.
Mr Comey wrote another letter on Nov 6, saying the e-mails did not change the FBI's earlier conclusion that there was no case against Mrs Clinton, but the damage was done.
On Nov 6, Mr Silver wrote on his blog that Mrs Clinton had an 81 per cent chance of winning before Mr Comey's first letter on Oct 28. By Nov 6, this was 65 per cent - with a corresponding loss in the popular vote.
"The pattern is at least consistent with a 'shock' caused by a burst of negative news for a candidate, as opposed to a more gradual decline,'' he wrote.
Mrs Clinton won the popular vote but lost the election by a wide margin on electoral votes.
Electors are due to cast their votes tomorrow and Republican electors are under public pressure to vote for someone other than Mr Trump - an outcome analysts say is unlikely.
Soon after the election, Mrs Clinton blamed the loss on Mr Comey's first letter, saying that it had raised "groundless" doubts and affected the momentum of her campaign.
A Republican, Mr Comey, 55, was appointed FBI director in 2013 by President Barack Obama. The job's term is 10 years. Only one director has ever been fired by a president.
Asked about Mr Comey last Friday at his last press conference as US president, Mr Obama said "it is always a challenge for law enforcement when there's an intersection between the work that they are doing and the political system".
He added: "And particularly in this hyper-partisan environment that we've been in, everything is suspect, everything you do one way or the other."
