Each day this week, the parties rolled out a new announcement, each with new spending. Despite a brief hiatus on Wednesday to welcome Canberra's first international flight – a moment of genuine excitement and opportunity – there are no signs the frenzy of spending promises will let up.

And while Liberal deputy leader Alistair Coe has a bank of spreadsheets where he tracks promises, even his fixation with figures got fuzzy last week. Coe dropped the ball on the redevelopment of Northbourne Avenue while announcing the Liberals' plans for two bus lanes and a cycle path when he suggested the Liberals might slow down the sale of Northbourne land and public housing.

The Liberals would be more strategic about it, he said, selling when there was demand for new apartments. Which might be sensible in itself, but completely ignores what the Liberals have said before: that they would continue with the programmed sale of Northbourne buildings by the 2019 deadline so they can keep the $60 million-plus in federal asset-recycling money. And second, that they would spend the money from those sales on a new hospital. Labor has budgeted that money to give the light-rail consortium as a lump sum at the end of 2018 or the beginning of 2019. Liberal leader Jeremy Hanson has already earmarked the same amount, throwing in an extra $20 million to make it $395 million, for his new hospital.

Which made Coe's musings on a slow-down in redeveloping Northbourne look confused and poorly thought through.

It's symptomatic of the mood that has gripped both parties as cash is thrown at voters in mind-boggling quantities. Labor is not only building a $710 million tram line from Gungahlin, it is promising another, this time heading over the lake with all the complicated engineering that entails.

The Liberals are not only building a hospital, they're building mini-hospitals in Gungahlin and Tuggeranong. Both parties are employing more than 50 new nurses.

The Liberals are spending perhaps $58 million on Northbourne. Both parties have promised tens of millions on new bus routes, drivers and electric buses. Both are widening roads in Tuggeranong and Gungahlin.

The Liberals are spending $85 million upgrading schools; Labor is spending $100 million. Labor is building a new school in Molonglo.

The Liberals are setting up an anti-corruption commission and pouring more money into the auditor's office. They're setting up a new defence industry group. They're scrapping the lease variation tax in town centres, which will cost $2.5 million a year. They're funding new health workers at the Winnunga Nimmityjah community group, a community radio station, a youth worker at the YWCA clubhouse and $400,000 on grants for veterans. They're upgrading Greenway Oval, Calwell ovals and local shops. They're reinstating police funding, buying Tasers for frontline police and installing flashing lights outside every school.

Labor is spending $17.5 million providing a tablet for every high school student. It's spending $250,000 a year on scholarships for teachers. It's funding postgraduate courses for nurses, new nurse-led walk-in centres at Weston Creek and Gungahlin, and meningococcal vaccines for children. It's spending $70 million expanding the women and children's hospital and $80 million a year on staff and operations. It's giving a tax break to clubs, worth about $1.1 million a year, setting aside $770,000 a year to attract more international flights, setting up a new bulky-waste collection service and providing more green bins.

There's more on both sides, but after a while you run out of breath, and attention. There are only so many promises a party can make before you feel sated, like when there's too many gifts under the Christmas tree and excitement turns into impatience and a slight self-disrespect as if you've been complicit in something distasteful.

But worse than losing the magic of Christmas, the promises threaten the integrity of the budget. Either the promises must be broken or the budget must blow out. There is a third alternative, and that is a tax increase or a significant savings measure. But to date, not one of the myriad promises has gone to that side of the government ledger.

The problem is fairly simple. This year, the government is set to bring in $5.05 billion in revenue. It is spending $5.42 billion. It's a difference of $380 million.

When you put that to Barr's team, they talk about the economy and their belief, hope or expectation that more economic growth and activity will bring the deficit into line. But it's a problem that in the eyes of many needs to be tackled much more actively than that.

The situation is also much worse than those figures suggest, with under treasurer David Nicol's pre-election update listing a series of projects that are yet to be incorporated into the budget in the next four years. They include design work on the Woden light rail, with the detailed stage one design, technical and financial work costing about $15 million.

City to the Lake is not in the forward estimates, other than $10 million for the new Point Park. The rest of the West Basin development cannot happen without funding.

The forward estimates don't include funding for increasing school enrolments, nor the operational costs for the new public hospital at the University of Canberra.

Nicol also lists about 40 programs for which funding runs out this year and another handful for which funding runs out next year. This year, the funding totals $43 million, and the projects will come to an end in July 2017 unless the government finds more money. This includes tourism and events money, projects helping families, people with disabilities and Aboriginal people, money for the RSPCA and for cleaning suburbs, the kangaroo fertility trial, weed control and the boost on surgery, and Nightrider buses.

And all of that before the landslide of election promises. Chief Minister Andrew Barr has been trying to work up a "black hole" narrative attacking the Liberals since before the election campaign began. But he's staring at a serious budget problem of his own.

In 2011-12, the budget fell suddenly into deficit, from which it hasn't recovered. In 2011-12, the budget forecast a return to surplus in 2013-14. The following year, 2012-13, the surplus was pushed back to 2015-16. The following year still predicted a return to surplus in 2015-16, but, alas, by the next budget the elusive surplus was pushed back to 2017-18. The 2015-16 budget set the surplus back yet again, to 2018-19.

This year's budget hung on to a surplus prediction for 2018-19 by its fingernails, but, by last week's update, it was pared back to just $16 million.

You would struggle to find anyone to put their money on that outcome. While the largesse falls during the election campaign like gentle snowflakes in a night sky, sadly it looks likely to turn to slush as we sleep.

Kirsten Lawson is the Canberra Times' chief ACT political reporter.