Just after 12.30 next Wednesday afternoon, Rishi Sunak will step aside from the Despatch Box and make way for Jeremy Hunt.
With the prime minister sitting just behind him on the government frontbench, the chancellor will then deliver a Budget which will make the political, as well as the economic, weather for the months leading up to the general election.
It is not overstating things to suggest that the contents of Hunt’s red box will determine whether or not the Tories have any chance at all of a record-breaking fifth term in office.
Sixteen months since becoming prime minister, Sunak finds his party in roughly the same place in which he found it - trailing Labour by around 20 points in the polls.
The Conservatives are running out of time, and the Budget is one of the few remaining opportunities they have to shift the political dial.
Many Conservative MPs, however, already believe that the game is up, the party is heading for opposition and there is nothing the chancellor can announce to change that fundamental truth.
“I don’t think he can do anything now to change the game because the game cannot be changed,” one gloomy former Tory minister told HuffPost UK.
“The Budget won’t really make any significant difference now to our chances of winning, therefore he should do some things that are attractive to Conservative voters, like reform inheritance tax, boost home ownership and help small businesses. I don’t think cuts to income tax would make any difference.”
The best thing Hunt can do, some Tories believe, is produce a Budget that appeals to the Tory base and ensures that as many of their MPs as possible survive when voters deliver their verdict later this year.
One veteran MP said: “What they should be thinking about is maxing the number of Tory MPs who come back after the election so we at least have a chance of getting back into government after one parliament.
“Labour have shown you can do that with 200 MPs, but with 150 it’s impossible.”
Other Tories are more optimistic, but warn that Rishi Sunak must not allow Hunt to waste this opportunity to change the political weather.
One senior Tory MP told HuffPost UK: “Rishi needs to own this Budget, not Hunt. The prime minister has more of a political instinct than the chancellor.
“This Budget is the last chance to start to reverse Labour’s dominance in the polls. The Budget must not be hijacked by an over-cautious Treasury.
“Number 10 needs to make sure the Budget is politically smart – not just economically smart.”
Former cabinet minister Damian Green, now chair of the One Nation group of moderate Tories, said: “The chancellor must seize the opportunity he has at the Budget to cut taxes, drive growth and put more money back into hardworking, ordinary people’s pockets.
“This is our chance to demonstrate to voters that we are on their side and that we are taking steps to alleviate pressures they face in all aspects of everyday lives. If we fail to do so, we risk the damaging consequences of a Labour government.”
In January, Hunt sought to compare himself with the Thatcher-era chancellor Nigel Lawson, suggesting that big tax cuts were coming.
Since then, however, the mood music coming out of the Treasury has changed, with sources confirming that there is less money available than previously hoped to pay for pre-election giveaways.
Hunt could even be forced to steal two of Labour’s flagship policies - scrapping non-dom tax status for wealthy foreigners and increasing the windfall tax on energy firms - to raise the money needed to cut either national insurance or income tax.
One Tory MP suggested that Hunt “cut and run” by producing a voter-friendly Budget before a May general election.
This would, though, fly in the face of Sunak’s previous declaration that the election would come in the second of the year.
Nevertheless, Labour campaign chiefs Morgan McSweeney and Pat McFadden this week gave a presentation to the shadow cabinet setting out why they believe a May poll is still “in play”.
One source said: “If they deliver a tax-cutting Budget and the economy looks like it’s starting to pick up, May could be the optimum time for the Tories to go to the country and still have some control over events.
“If Sunak leaves it till the end of the year it looks as if they are holding on till the bitter end, and as we saw with John Major in 1997 and Gordon Brown in 2010, that doesn’t usually end well for the government.”
HuffPost UK has also been told that deputy leader Angela Rayner will play “a central role” in the Labour election campaign.
Relations between Rayner and Keir Starmer are professional rather than warm, with the leader being closer both personally and ideologically to shadow chancellor Rachel Reeves.
But one senior Labour insider said: “Angela appeals to certain voters in a way that Keir doesn’t, so she will be a key figure when the campaign gets underway.
“We want the public to see Keir, Rachel and Angela out there together making the case for a Labour government after 14 years of the Tories.”
Whenever the election takes place, next Wednesday’s Budget will go a long way to determining whether it’s nearly time to call last orders on Sunak’s time in Downing Street.