Ed Miliband is a much more impressive speaker in the flesh than he is on TV.
That's not much of an endorsement but it merits noting for what it says about the tyranny of the visual in our politics.
Mr Miliband is sincere, bright, policy-focussed, and has ideas for achieving the kind of Britain he wants to see.
An undecided voter who sneaked into the main hall at the Scottish Labour conference in Edinburgh on Saturday might have been surprised by the power of his performance.
They would have seen the determination and heard the righteous tremor in his voice as he excoriated the Tories and their austerity policies.
He intoned: "They are a party that defends a country with bank bonuses unchecked and food banks on the rise. They are party that refuses a Mansion Tax and imposes the cruel and unfair Bedroom Tax. A tax we will abolish across the whole of the UK as soon as we get into government.
"They are a party that assaults the tax credits of working families and lets the tax avoiders off the hook. They are a party that cuts funds for the most vulnerable and stands up for the hedge funds. Whenever there is a choice to be made, they always make the wrong choice. The unfair choice. The choice for the few.
"Think of what has happened to working families since they came to power. Wages down by £1600. Zero hours contracts exploding. Insecurity at work. Opportunities denied to the young. Promises broken. It is a record they can't defend."
His logic was prosecutorial but his tone was pure white burning indignation.
Aye, there's the rub. Mr Miliband can lecture us all on what is wrong with the country, and he can even propose plausible policy remedies, but he can't convince enough people that he is the man to carry these changes through.
On television, he comes across as awkward, geeky, and blandly earnest, like a well-meaning sixth former making a speech at the school assembly on the evils of animal testing or the destruction of the rain forest.
This fits the caricature of Mr Miliband fashioned by the right-wing press but their cruel cartooning reflects public feelings about the Labour leader as much as it shapes them.
He looks odd, thanks to a rubberish, hyper-expressive face that could have been animated by Acme. Every time he opens his mouth, you expect him to gaffe and even when he doesn't it seems a case of sheer luck rather that competence or confidence. He projects weakness when he manages to project anything.
A good and decent person no doubt he is but he doesn't talk, walk, or carry himself like a man on the cusp of power in the world's fifth largest economy.
The spectre that stalks Ed Miliband is not the jibes of the Daily Mail or the braying of Tory backbenchers every Wednesday lunchtime. It's the unshakeable feeling, elusive as smoke but just as real, that he is simply not a leader, not a Prime Minister.
It's all grossly unfair but then so is life. Man is imperfect and imperfectible.
None of this would matter if the general election weren't so close. In Mr Miliband, Labour has a leader less popular in Scotland than David Cameron just at the very time when they need a figurehead who connects with voters north of the border.
When the unions installed 'Red Ed' over his Blairite brother David, many on the right of the party predicted it would lose them Middle England. They could never have imagined it might lose them Scotland too.
Of course, the referendum has played a large part in the collapse of Labour's vote but a more confident, assured, and commanding leader could have made an appeal to the less militant Yes voters.
He or she could have said: "I know independence is important to you. I respect that. But throwing out the Tories and creating a fairer and more prosperous society is important to all of us. The constitution isn't going to be changed in 60 days, so let's work together in our shared interests until May 7 - and join battle again on May 8."
That is not Mr Miliband or, just as important, not the perception of him.
This impolite truth was there for all to see when he and Scottish Labour leader Jim Murphy shared the stage.
Mr Murphy spoke with passion and without notes. He talked about the achievements of Labour - the NHS, the Race Relations Act, the minimum wage, and the Scottish Parliament - but it was not a speech anchored in the past. He sketched out a vision for the future of Scotland, one both more left-of-centre than we're used to hearing from Labour politicians and yet at the same time attuned to the economic realities of the day.
He told the hall: "We are determined to win not just because we want a Labour government but because those people who are genuinely in the fight of their lives need a Labour government. We are determined to win for the mother, the business owner and the pensioner."
And he appealed to Labour voters flirting with a vote for the SNP to stay on board:
"I know that there are Labour supporters thinking of switching to be SNP voters this time. And I've met and listened to a lot of those undecided voters and I know that you are desperate for change. So are we.
"I hear your sense of frustration about how you work harder and feel no better off. What I want to set out to you and the rest of Scotland is that Labour is that change. We will stop a decade of Tory rule, end Tory austerity, prevent their cut of £2.7 billion to Scotland."
As is the case with all the parties, there was little in the way of fresh policy announcements. One, however, was a pledge to restore student support cut by the SNP and boost college bursaries by £1000 per head. There would also be a "future fund" of £1600 for 18 and 19 year olds not at university, college or undergoing an apprenticeship to help them get into work.
If Mr Murphy was light on policy, the same could not be said for vigour. He spoke with an intense empathy for the injustices suffered by vulnerable people under the Conservatives and optimism that Labour could help those people back onto their feet. This wasn't just another conference speech but a vivid piece of evangelism for the redemptive, uplifting power of government and social action.
Where Mr Miliband damned the Tory worldview, Mr Murphy put forward a vision of his own. Where Mr Miliband talked like a critic of coalition policies, Mr Murphy spoke like someone who had alternative ideas and could do something about them. Where Mr Miliband sounded like the Leader of the Opposition, Mr Murphy sounded like a leader. More than that, he looked like someone who should be setting his sights higher than First Minister of Scotland.
Sound a bit far-fetched? Fine. Here's a test: Close your eyes and picture the famous black door of 10 Downing Street. Imagine Ed Miliband standing outside it, knowing that beyond the door lies the Cabinet room where decisions of life and death, war and peace are made. He looks out of place, doesn't he? Now imagine Jim Murphy standing there.
There were two leaders on stage in Edinburgh today but only one Prime Minister.
Stephen Daisley is STV's digital political correspondent. You can contact him at email@example.com.