IF there was a general election in the morning, Fine Gael and Labour would be returned to power with a very comfortable majority – the opinion polls are very clear about that. But exchanges between the two parties have become increasingly testy in the past couple of weeks and it is far from clear what the two parties' programme for government would be.

Nowhere is this more obvious than with the banks. Labour, which was at the centre of an embarrassing gaffe last week when Eamon Gilmore appeared to misunderstand the government's Nama proposal, has proposed nationalising the banks, while Fine Gael has strongly argued against this approach.

On taxation, Fine Gael has (somewhat improbably) insisted it would keep tax rates intact, whereas Labour has advocated a new 48% tax rate.

The main opposition party's tough line on the public sector – both in terms of pay and reform – is also in direct contrast with Labour's recent efforts to keep public sector workers sweet. Fine Gael wants to freeze public sector pay and increments, while Labour wants pay frozen only for those earning more than €200,000 – a tiny percentage of the public service. It also wants to reverse the pension levy on lower paid civil servants.

Fine Gael is also more aggressive on cutting government expenditure, arguing that two-thirds of the cost of bringing the public finances back into line should come from cutbacks and efficiencies in the public sector. Labour, in contrast, have been very vague about cuts in expenditure and have spoken about the need to reflate the economy, although how that is achieved in such an open economy is questionable.

Labour is an enthusiastic backer of social partnership, while Fine Gael is lukewarm on the notion, particularly given its determination to tackle inefficiencies in the public sector.

It is no exaggeration to say there is a gulf on virtually all the key economic issues between the two opposition parties.

On one level, this doesn't really matter. Let nobody be in any doubt that if the seat numbers add up after the next general election, Fine Gael and Labour will do the business and form a government. Politics being politics, that is inevitable.

But if, as many believe, that election comes sooner rather than later, the policy differences between the two components of the most likely government are definitely a concern.

If and when Fine Gael and Labour do get into government, there can be no repeat of what happened with their coalition of 1982-1987. Back then, Alan Dukes' efforts to bring order to the public finances were consistently vetoed by Labour ministers concerned about the impact of cutbacks. The result was an ineffective government and a stalemate for the duration of the coalition's spell in power.

That failure to address the crisis in the public finances – allied to Charlie Haughey's initial reluctance to take the tough decisions during his first two spells in government – was disastrous for the country. The 1980s was a wasted decade, where tens of thousands of people emigrated each year and unemployment was consistently in the high teens. It was only in 1987, nearly a decade after the problems first became apparent, that Haughey – at the third time of asking – and Ray MacSharry finally did what was needed.

It's true that the Fine Gael-Labour-Democratic Left government of 1994-97 was much more successful on the economic front. However, the economic conditions were much more favourable and, in Ruairí Quinn, Labour had a finance minister who was economically literate and determined to prove that his party could be trusted with the national finances.

Labour is touchy about criticisms that it is adopting a blatantly populist approach to the current economic crisis. But there is little evidence today of Quinn's hard-headed economic orthodoxy.

There is no question that, politically, Labour's strategy is paying dividends. Fine Gael is storming ahead in the polls but don't be surprised if the smaller opposition party emerges as the real winner on 5 June.

If Labour gets to government, it will need to take the kind of difficult decisions it is currently sidestepping. It would be naive to expect Fine Gael and Labour to agree to a joint programme at this stage – the two parties are doing just fine on their own. But given that both parties have categorically ruled out a coalition with Fianna Fáil, at some point between now and the next election, they need to start singing from something approaching the same hymn sheet. In the worst recession in living memory, the national interest – and their own self-interest – requires that the alternative government set out its stall before coming to office.

Fine Gael strategists are conscious of this. They know that, with Fianna Fáil in unprecedented disarray, there is a huge opportunity for the opposition. But they cannot afford to be bickering around the cabinet table on how best to tackle the country's problems. If both parties are to attain the not unrealistic goal of eclipsing of Fianna Fáil as the natural parties of government, the lessons of the 1980s' coalition must be learned. For all our sakes.