By Mike Sergeant
Political correspondent, BBC News
Nick Clegg has a big chance to shine in the TV debates
Liberal Democrat leader Nick Clegg has spoken of his desire to be prime minister one day - an ambition that might have brought smirks from his political opponents in the past.
Polls in recent months have wiped the smiles off a few faces. Not because the Lib Dems have been powering ahead in surveys of public opinion - they have not.
But the closer the battle between Labour and the Tories, the more important Mr Clegg might become.
He has said he will not be the "kingmaker", and that it is up to the British people to choose the next government. But he also knows that this might be the best sniff of power the Liberal Democrats have had in a very long time.
One of the biggest challenges for any Lib Dem leader is visibility. How do you get people to focus on you and your policies if they think you have very little chance of government?
That will not be such a problem this time. The multilingual Mr Clegg and his Spanish wife will get their fair share of the limelight, and the scrutiny.
And, when it comes to the TV debates, many Lib Dems can scarcely believe their luck. On the three big nights, their man is guaranteed equal billing with David Cameron and Gordon Brown.
Mr Clegg needs to use the platform carefully - and not let his opponents play "piggy in the middle" with him.
Some observers think he needs to show more of the charm he often displays in small groups and less of the angry Clegg we sometimes see in public.
There will be lots of talk during this campaign of what roles senior Liberal Democrats might be offered in a coalition. Or what the conditions might be for supporting a minority government in Parliament. But party officials say indulging in such speculation at this stage is pretty pointless.
Mr Clegg and his team know they cannot campaign for a hung Parliament or give the slightest hint of cosy pre-election arrangements with Labour or the Tories.
It would risk splitting the party and send completely the wrong message to their activists fighting hard to win tight marginal seats.
Anyway, a hung Parliament might not happen. Our electoral system tends to produce a decisive result, whatever the opinion polls suggest in the election run-in.
What about policies? We can expect the Lib Dem leader to repeat his four big themes ad infinitum.
They are: fair taxes, more money for schools, a rebalanced economy and cleaning up politics. You will hear plenty about them during the campaign.
What the Lib Dems do not have this time, though, is a rallying cry equivalent to their opposition to the Iraq war. In 2005 this was a really distinctive element to their campaign.
Nick Clegg's opponents will attack ferociously - and seize on any hint of muddle and inconsistency. His challenge over the coming weeks is to give his party enough clarity and appeal to be treated as real contenders.