Image copyright Getty Images Image caption The pair seemed to go from bad to worse in 2010
Former vice-president Joe Biden is mulling a 2020 presidential bid.
Two reasons why a Trump administration official might be able to help a Democrat – namely former FBI director James Comey.
Reuters suggests Mr Comey could provide Mr Biden with a political lifeline. It reports Mr Comey is said to be planning a months-long bus tour to mark his book’s release on 9 October.
Mr Comey has not commented on the reports.
What does this have to do with Mr Biden?
There are two things.
One is whether Mr Comey would ultimately approve a US presidential campaign.
For some time Mr Comey was reported to be part of the book-promotion caravan – after all, he was the man who broke the news that Hillary Clinton’s emails were being investigated.
But that was his role then. Mr Comey is still widely respected for his integrity and character – he is noted for treating Mrs Clinton and Mr Trump equally professionally.
Donald Trump’s presidency, on the other hand, has been nothing short of tainted by the president’s own flagrant ethical failings.
But if that taint becomes too great, the high-profile bus tour seems to suggest Mr Comey may take the next step and endorse Mr Biden for president.
Speaking at a rally, Donald Trump Jr told reporters he does not think his father “would be popular” if Mr Comey endorsed Mr Biden for president.
But then he added: “A lot of people will.”
Two, what if Mr Comey opposes Mr Biden? This does not seem to be of any immediate concern for Mr Biden, because he has repeatedly distanced himself from Mr Comey’s criticisms of Mr Trump.
In his bestselling book, A Higher Loyalty, Mr Comey describes a 2016 meeting he had with Mr Biden.
He writes that, in the meeting, Mr Biden told him he was “over it”, and that, “he had moved on.”
Mr Biden has always denied this.
Image copyright Getty Images Image caption Mr Comey said he cannot tell Donald Trump to resign
It is also worth noting that while Mr Comey made critical remarks about Mr Trump, most of his opposition does not come from concerns about his personal character, but rather his handling of the investigation into his campaign’s links to Russia.
He said: “The best path forward would be for President Trump to resign.”
So is it possible that there are divisions within the US government, and that these may serve as a stumbling block for the Democrats if they are to win the White House in 2020?
BBC reporter Ben East told the Today programme that, from a personal point of view, it is “very interesting” that Mr Comey has endorsed Mr Biden.
“That does show that things have moved on,” he said.
“There is no doubt a great deal of vitriol that has been directed at Jim Comey since his last public comments last year.”
Read more: Trump and Comey tension shows no signs of dying down
Image copyright Getty Images Image caption Donald Trump has called for the FBI director’s political “total and complete shutdown”
What about this bus tour? Is it really going to happen?
Reuters says that, on Saturday, Mr Comey is expected to visit numerous cities around the country.
But is he really saying that he is going to back Joe Biden for president?
That depends on what you mean by support.
Reuters reports he says he is an admirer of Mr Biden.
Then again, there are many who don’t like the book, and also think Mr Comey is to blame for Mrs Clinton’s defeat.
Mr Comey, and his old friend Mr Biden, need more than positive words from one another to take Mr Biden to the White House.
Mr Comey writes about the damage he caused Mrs Clinton when he re-opened the email investigation, days before the election.
“I wanted to be the adult in the room,” he says in his book.
“Yet I was unable to be that adult. In doing so, I became a child. That’s a nightmare you don’t want to wake up from.”