Amid all the hullabaloo about debates we mustn’t forget the biggest guaranteed head-to-head clash of the election campaign: the final Budget of this parliament, on 18th March.

As George Osborne gets to his feet before a packed House, it will be the last really big moment to change perceptions of the Coalition. Manifestos and leaflets can make promises, but only the Budget has the potential for sizeable and instant changes in government policy. Inevitably, the rumour mill is already pumping out a variety of possible announcements (Raising the NI threshold? Cutting beer duty again? Giving away RBS shares to all as a reward for those tough times?).

We know the negative potential of Budgets – either to sabotage the other side (the Conservatives are still grappling with Darling’s 50p tax rate, even though it was only in place for a few weeks before the 2010 election) or for a Chancellor to trip himself up (the 2012 “omnishambles” Budget precipitated a fall in poll ratings from which the Tories have yet to recover), but their potential for positive electoral gains are more in doubt. Even the bounce from the Autumn Statement, which gained a huge amount of support for its pension reforms, proved temporary. Osborne will be hoping to deliver a double whammy, pitching an offer that is sufficiently attractive that it secures votes long enough to last until polling day while also casting Labour into chaos by forcing them to back or oppose something popular but in conflict with their worldview.

Details aside, this is favourable Conservative territory – effectively a televised debate between the Chancellor and Ed Miliband (and then Ed Balls) specifically on our party’s strongest territory, the economy. Not only do Labour lack public trust or policy coherence on the topic, but Balls and Miliband have traditionally failed to deliver anything like their best performances in response to Budgets, tending to scrabble for an answer before others try to pick holes over the following days.

While the Conservatives weigh up how to make the most of the big moment, it’s worth noting how little activity is coming from the Lib Dems on the topic. Most of their MPs (including a variety of Ministers) are concerned about hanging onto their own seats in May, and are therefore somewhat distracted. Collectively, that distraction appears to be feeding through to their leadership – we’re told that the yellow part of the Coalition is not putting forward many ideas or objections for the Budget at all.

The Lib Dems’ failure here is in keeping with their wider strategic problems – the whole approach to this election was meant to be about showing their power as a brake on Tory views and on differentiating or even decoupling themselves from the “Tory-led government”. That’s the job that Ryan Coetzee was meant to be doing, first in Downing Street and now in Lib Dem HQ, though it simply doesn’t appear to be working very well. Their tagline is “Stronger economy, fairer society”, but there’s a distinct lack of any co-ordinated campaign to prove that either has anything to do with them being in Government.

At minimum they need a public battle with the Chancellor on the right kind of issue (and even then they will struggle to persuade many voters to believe them) – but it’s possible there aren’t enough of their MPs left around Westminster with time on their hands to actually deliver one.

That should make Osborne’s job rather easier. He’s in training for his big day, Rocky-like, knowing how much relies on him pummelling his opposite number, and the removal of any Lib Dem hands holding back his arm can only be a boon. The longer the polls remain essentially tied, the greater importance the Budget takes on as a moment for the Conservatives to break through. No pressure, Chancellor.