Going through security at Tampa airport just before new year, I realised something: these people are not being paid. For Britons and Europeans this is bizarre. Even Venezuelan government employees get paid, though the money may not be worth much when they come to spend it. While government shut-downs are common in the US, this one may be of a different order of duration. Here’s why...

Donald Trump’s instincts are those of a property developer and TV show host. We saw the first just before Christmas when he urged the Federal Reserve not to increase interest rates, for developers like cheap money. It didn’t work: the Fed went ahead. If it slows the pace at which rates rise this year it will be because of the data on the US economy, not presidential pressure.

Now he’s gone into show host mode again with his prime-time address from the Oval Office, seeking to put pressure on congress to release government funds to build his proposed Mexican border wall. This was his first-ever use of that format, the modern form of his predecessor Theodore Roosevelt’s “bully pulpit”. It does not look like as though this has worked either.

This is partly because his line – that the US faces an extreme national threat from immigration – is simply not credible. There are lots of threats the US faces, but it is hard to argue this should be top of the list. It is also because the new Democrat majority in the House will, just like the Fed, want to assert is its independence. Indeed it has to: it has to show where power lies. We are seeing a classic example of the adage that “the president proposes, but congress disposes.”

So how will this end? The general agreement among US political commentators is that this will be a long-running show. It is pretty rough on those federal employees that have to continue working and paying their bills while waiting patiently for a back payment of their wages, but it suits both sides politically to have a punch up. There will be a deal in the end, just as property developers that are under financial pressure have eventually to do a deal with their banks. But Donald Trump will string this out as long as he can – as he has, in his earlier incarnation, done in the past.

Who could be running against Trump in 2020? Show all 23 1 /23 Who could be running against Trump in 2020? Who could be running against Trump in 2020? Joe Biden The former vice president - poised to be a frontrunner - has announced his run. He recently faced scrutiny for inappropriate touching of women, but was thought to deal with the criticism well AFP/Getty Who could be running against Trump in 2020? Bernie Sanders The 2016 runner-up has announced that he will be running again in 2020 Getty Who could be running against Trump in 2020? Hillary Clinton The 2016 Democratic presidential candidate and former Secretary of State says she is “still considering” whether she will run again. Getty Who could be running against Trump in 2020? Pete Buttigieg The Indiana mayor and war veteran will be running for president. If elected, he would be the first openly LGBT+ president in American history. Getty Who could be running against Trump in 2020? Kamala Harris The former California attorney general will be running for president in 2020. Introduced to the national stage during Jeff Sessions’ testimony, she has endorsed Medicare-for-all and proposed a major tax-credit for the middle class. AP Who could be running against Trump in 2020? Elizabeth Warren The Massachusetts Senator has formally launched her bid for president in 2020. A progressive Democrat, she is a major supporter of regulating Wall Street. AP Who could be running against Trump in 2020? Beto O’Rourke The former Texas congressman told Oprah Winfrey that he “has been thinking about running for presidency”, but stopped short of formally announcing his bid to run in 2020. AFP/Getty Who could be running against Trump in 2020? Wayne Messam Mayor of the city of Miramar in the Miami metropolitan area, Wayne Messam has announced his bid. He intends to run on a progressive platform against the "broken" federal government. He favours gun regulations and was a signatory to a letter from some 400 mayors condemning President Trump's withdrawal from the Paris Climate Accord. Vice News Who could be running against Trump in 2020? Kirsten Gillibrand The New York Senator formally announced her presidential bid in January, saying that “healthcare should be a right, not a privilege.” Getty Who could be running against Trump in 2020? Cory Booker The New Jersey Senator has announced that he will be running for the presidency in 2020. If he secures the nomination he said finding a female vice president would be a priority. Getty Who could be running against Trump in 2020? John Delaney The Maryland congressman was the first to launch his bid for presidency, making the announcement in 2017. AP Who could be running against Trump in 2020? Julian Castro The former San Antonio mayor announced his candidacy in January and said that his running has a “special meaning” for the Latino community in the US. Getty Who could be running against Trump in 2020? Tulsi Gabbard The Hawaii congresswoman announced her candidacy in January, but is likely to face tough questions on her past comments on LGBT+ rights and her stance on Syrian President Bashar al-Assad. Getty Who could be running against Trump in 2020? Andrew Yang The entrepreneur has announced his presidential candidacy, and has pledged that he would introduce a universal basic income of $1,000 a month to every American over the age of 18. AFP/Getty Who could be running against Trump in 2020? Marianne Williamson The author and spiritual advisor has announced her intention to run for president. She had previously run for congress as an independent in 2014 but was unsuccessful. Getty Who could be running against Trump in 2020? John Kerry The former secretary of state has said he is still thinking about whether to run. Getty Who could be running against Trump in 2020? Michael Bloomberg The entrepreneur and former New York mayor– with a net worth of around $50bn – has said he will decide by the end of February whether to seek the presidency. AFP Who could be running against Trump in 2020? Howard Schultz Former Starbucks CEO Howard Schultz has not yet ruled out running for president in 2020, despite criticism that his bid could help re-elect Mr Trump by dividing the Democrat vote. AP Who could be running against Trump in 2020? Eric Holder The former attorney general has said he will decide in “the next month or so” whether to run as a 2020 presidential candidate. AP Who could be running against Trump in 2020? Eric Swalwell The California congressman said he is “ready to do this” and will decide before April whether to run. MSNBC Who could be running against Trump in 2020? Terry McAuliffe The former Virginia governor, who worked to elect Democratic governors during 2018 midterms, said there was a “50 per cent” chance he would run. AP Who could be running against Trump in 2020? Sherrod Brown The Ohio senator is still undecided about whether to run for president in 2020. Who could be running against Trump in 2020? Mitch Landrieu The former New Orleans mayor said he doesn’t think he will run for president, but “never say never”. AP Photo/Jacquelyn Martin

The pressure to settle will eventually come from the US economy. There are several points here. First, the economy is already slowing a little, and the R-word (recession) is starting to appear in financial commentaries. Second, the break in share prices in the final weeks of last year will have had consequences that have yet to emerge. Third, there is now more pressure on the president to do the trade deal with China – he needs a success story, and the US economy needs a deal. China has moved a long way to meet US concerns, and that will help him here. But none of this will force both sides towards a conclusion. Indeed, a trade deal with China actually strengthens Donald Trump’s position in the stand off as he could argue that the Chinese are more reasonable than a Democrat-majority congress.

There is, however, a long stop: the US debt limit. A new paper by Bank of America Merrill Lynch Global Research, which I have seen this week, notes that the shutdown risks a fight over the much more important debt limit. The treasury is alright until early March but after that, in the absence of an increase in the debt ceiling, it will have to start what are called “extraordinary measures” to pay its bills. It runs out of cash in August.

Support free-thinking journalism and attend Independent events

I cannot conceive that the shutdown will run through to August, but financial disruption will come much sooner. It is not in the self-interest of the president to have bumpy markets through the spring, because they will undermine the economy in the longer term. He does not want a recession on his watch, and absolutely not in the run-up to the November 2020 elections.

Markets are both a reflection of economic confidence and a determinant of it. We are seeing a wobble now in the markets but that has not yet transmitted through to the real economy. Reason says that it is in the self-interest of both the president and the Democrats in congress to do the deal on the border wall, if only to square up for the much bigger fight over the debt limit. But it may take a while for reason to prevail.