As he walked off stage at an event with David Cameron early in the year, Nick Clegg fell victim to the worst of modern political pitfalls - the open microphone.
"If we keep doing this, we won't find anything to bloody disagree on in the bloody TV debate," the audience heard him say to the prime minister.
How things changed.
A referendum on the voting system was the price Nick Clegg demanded for entering coalition, but in May it was comprehensively thrown out by the voters - almost seven in 10 saying "no" to AV.
However, it was the bitterness of the attacks by Conservatives on Nick Clegg himself that riled many Lib Dems, including former leader Paddy Ashdown, who described the campaign as "deeply and appallingly personal" and urged Mr Cameron to distance himself from it.
Many thought losing the referendum might end the coalition altogether. It didn't, though the disagreements continued.
The pressure on Mr Clegg from his own party, particularly over the NHS shake-up, was intense - especially at his spring conference.
'A good kicking'
The leadership was resoundingly defeated in a vote on the conference floor, and the Lib Dem leader successfully fought for a pause in NHS plans for further consultation.
Meanwhile, the electorate was not just rejecting Lib Dems over changing the voting system.
The Barnsley by-election saw the party thrashed - falling from second to sixth place and losing their deposit.
The past masters of the by-election campaign were humiliated. The party's candidate Dominic Carman conceded he'd received "a good kicking" from the voters.
The English local elections also saw the party thoroughly beaten, losing control in almost half the councils up for election and shedding 750 seats - the worst performance in decades.
The Scottish Parliamentary election was also a disaster, in the words of the then leader in Scotland - nine first-past-the-post seats lost to the SNP. Wales wasn't much better.
Mr Clegg also had to deal with internal problems. One of his fellow Lib Dems in cabinet, Chris Huhne, faced a police investigation over claims by his former wife that he asked someone else to take speeding points on his behalf - a case that is still not resolved.
And some activists wanted Mr Clegg to show a bit more grit - one Lib Dem councillor urging him in April: "Can you not have just a slight argument with Mr Cameron?"
Interventions like that brought speeches on "muscular liberalism" and the spin doctors began to work hard on persuading journalists that they were winning coalition battles over banking reform, benefits uprating and latterly, even Europe.
But Lib Dem influence was not sufficient when it came to the Cameron veto at December's EU summit.
And Mr Clegg's failure to appear in the Commons chamber when the prime minister reported back was seen by some commentators as weak.
He didn't disguise his annoyance over the summit outcome in interviews - telling the BBC's Andrew Marr it was "bad for Britain" and he was "bitterly disappointed".
Mr Clegg will be glad to see the back of 2011.
He's had his fair share of difficulties and his party appears to be taking the brunt of the public mood, scarcely getting into double figures in the opinion polls.
In recent weeks he has tried hard to create more definition for the Lib Dem brand - with his ideas on the open society - but even in power, his party is worried that their survival at the next election is under threat.