Bernard Ponsonby preview as Humza Yousaf, Ash Regan and Kate Forbes debate for SNP leadership on STV

On Tuesday evening at 9pm, live on STV, the contest to be the next leader of the SNP and First Minster of Scotland takes off in earnest.

Humza Yousaf, Ash Regan and Kate Forbes will not face an audience of sympathetic activists.

Nor will they be invited to give a clip for the news, the kind of soundbite which does not come with a serious interrogation of the content of the answer.

For the first time, nerves may feature as they realise that over an hour of live television in a demanding format could sink their campaign with a slip of the tongue.

Tomorrow, a clear frontrunner may emerge, or a candidacy could be sent to the knackers’ yard.

STV’s political editor Colin Mackay will ensure that answers which evade or are platitudinous, or embrace a love of waffle, will be punctured by a simple act of interrogation.

And since the format allows the candidates to cross-examine one another, they have a number of questions to address by way of preparation, not least how attack-focused they want or need to be.

SNP members looking on will see all three taken out of a comfort zone and placed in the kind of environment every First Minister has to contend with on a daily basis.

Yes, television can be slightly artificial in that it can sometimes allow performance to mask shallowness, but its main attribute is that it is unforgiving of someone who is not up to the job.

This is not an easy gig.

These contests demand that candidates set out policy and strategy for debate and give a clear indication of the path they will follow should they emerge victorious.

I watched last Wednesday night’s exchanges in Cumbernauld and was surprised at the amount of off-the-top-of-the-head thinking going on. At one point, Regan had an answer on financing councils that floated a land tax and then a reformed council tax and then going back to the drawing board altogether.

This kind of exercise in filling space won’t really do. Voters have a right to expect that those who seek to lead have thought about policy and where they want to take the country.

The problem is that making commitments in a contest to take you over the winning line might not necessarily stand up to scrutiny. A pledge in a debate might simply not be deliverable when it comes to enactment.

Pledging what you can’t deliver because you haven’t done the heavy lifting on the thinking front would simply hardwire a crisis into your leadership.

And let’s be brutally honest. Setting the independence question aside, the key issue is how Scotland’s public services are put on a sustainable footing that allows them to meet future challenges and at the same time drags them from the crises that currently envelop them.

There are no easy answers to this and don’t expect candidates to have a ready-made solution, properly costed and deliverable even before they enter Bute House.

And yet if they are simply too vague and adopt a ‘let’s wait’ position, they risk losing votes to their opponents.

Of course, voters are irrelevant in this contest if they are not members of the SNP. What exercises SNP members might not exercise the electorate at large.

The debate around delivering independence is all consuming within SNP circles.

And within the wider ‘Yes’ movement, there is a feeling that all three candidates are safety-first politicians who will embrace the managerialism of the current First Minister, who simply refuses to live dangerously of even riskily on the independence question.

On the one level, there is no obvious, deliverable strategy to achieve a second referendum, since constitutionally it is not within Holyrood’s gift to deliver it.

Winning elections and waving mandates at Westminster has failed on numerous occasions, and declaring a unilateral declaration of independence would be a gesture with no legal consequence and one that would hold a government up to international ridicule.

The problem for the SNP is that any lack of agitation might just kickstart Alex Salmond’s Alba Party, who seek to give the broader movement an insurgent edge.

The new leader has to pick up the pieces of a strategy that shattered when Sturgeon quit. Do they continue with the ‘de-facto referendum’ line, refine it or bin it?

The SNP as a party of government with a radical constitutional aim is at a crossroads. If they elect a leader who is not up to the task, both party and cause could go into reverse.

I have doubts about the abilities of all three candidates and believe none of them possess the range of skills both intellectual and presentational to deliver for their party and the country.

Tomorrow night at 9pm, they have the chance to prove me wrong.

Scotland’s Next First Minister: The STV Debate is on STV and the STV Player at 9pm on Tuesday, March 7, with live reaction and analysis on the STV News website.