Ahead of this week's Budget, Ed Balls (who I profile in the current NS) and George Osborne made their usual appearances on the Andrew Marr show. The best moment, as ever, came after their separate interviews when they appeared together on the studio sofa.

After Marr raised the subject of the TV debates, Balls ambushed Osborne by inviting him to shake hands on a head-to-head contest between them before the election. "Come on, George, let's go for it," he said. The Chancellor acceded, telling Balls, "I'm happy to meet you in a debate", and shaking his hand. But no sooner had he done so than he added: "Well, we're going to see who else wants to be invited ... I've got a very effective Chief Secretary [Danny Alexander] who I would think would also want to be part of that debate", prompting Balls to reply: "No, no, one-to-one, we just shook on it". It was a brilliant manoeuvre by Balls, although the image of him shaking hands with Osborne will doubtless by exploited by the anti-austerity Greens, SNP and Plaid Cymru.

In their earlier interviews, both men sought to deploy their standard attack lines but were distracted by the question of how they would behave in a hung parliament. Pressed repeatedly on whether Labour would do a deal with the SNP, Balls refused to rule one out, telling Marr: "You know, Andrew, you've been covering politics for 30 years, parties, large parties, at this stage say 'we're fighting for a majority'". When asked whether the Tories could work with Ukip (Nigel Farage has offered to support them in return for an EU referendum before Christmas), Osborne similarly said: "We are going to get ... we are fighting for a majority. We only need 23 more seats to get that majority".

But both men's answers betrayed their lack of confidence in winning outright. Balls's suggested that he was obliged to maintain the pretence that Labour is fighting for a majority, even if one is unlikely, while Osborne began by saying that the Tories would win a majority before reverting to "we are fighting" (he knows that the former is extremely unlikely). The reason neither of them is prepared to rule out working with the smaller parties is precisely because they may need to do so.