Liberal Democrat ministers will seek to respond to the party's difficulties after the tuition fees vote by stressing the difference the party is making in government.
But Liberal Democrat voters do not agree with them about that.
On most issues, the majority of those who voted LibDem think that party has made no significant impact, for better or for worse.
The main exception is university fees - but that isn't good news either. Fully 49% of those who voted LibDem think the party's presence in government made the policy worse than it would have been, while only 11% think they improved it. That will strike LibDems as harsh - they will point to the policy concessions they tried to get in the detail of the scheme, but the brute political fact is that the Conservative minority couldn't have done any of it without them. In any event, when it is their own voters who are four times more likely to say that the policy was made worse by LibDem output, it shows how much their change of position rankles with their supporters.
These are perhaps the most striking findings of Michael Ashcroft's extensive LibDem specific polling, reported on ConservativeHome, where you can read the full PDF.
The perceptions held by LibDem voters do not strike me as entirely fair. They are surely right that the party has made no difference on spending cuts - we know from both Nick Clegg and David Laws' account that the LibDems did not seek to negotiate or substantively shift the Conservative policy - and it is plausible to say the same about defence and housing benefit among other areas.
Strangely, the areas where their own voters are most likely to say they have made no difference - Europe and Crime/Sentencing [and possibly environment (*), though the correct data there is unclear] - are those where LibDem ministers probably have the strongest policy evidence for having shifted the government's approach in a way that most LibDems, and broader centre-left opinion, would welcome. (And they get most credit for having an influence on welfare reform, where it is rather harder to see a distinctive LibDem contribution to the government's agenda, which has been driven by Iain Duncan Smith).
Here are the findings as to where those who voted for LibDem MPs in May feel the party is or isn't making a difference in power:
No difference: 46%
Changes to housing benefit
No difference: 50%
University tuition fees
No difference: 41%
No difference: 57%
No difference: 65%
No difference: 53%
Crime and sentencing
No difference: 67%
No difference: 65%
No difference: 45%
No difference: 62% [?*]
* There must be a typo in the Ashcroft publication on environment numbers, which add up to 115%. (It may well be that 'no difference' should read 47% rather than 62% though that is a guess. At least one of the three figures must be misreported).
The poll is of 2000 people who voted Liberal Democrat in May 2010 in seats which the party won, conducted between 18th and 29th November 2010.
There may be two lessons for the LibDem Parliamentary party.
One may be that overclaiming doesn't work if the details don't stack up.
For example, the government plans to get on the front foot by heradling the "pupil premium" tomorrow. It is a good idea, but they have failed to deliver it, which means that boasting too much about it may backfire.
The policy announced will, in fact, break the promise in the Coalition Agreement that ""we will fund a significant premium for disadvantaged pupils from outside the schools budget", so the 'premium' is now being funded by cutting spending for most schools instead. So it will be necessary to watch the detail carefully to see if the perverse consequence is to take money away from schools with the most disadvantaged pupils.
Secondly, the polling results will play into the central strategic debate among LibDems who continue to believe they can make the Coalition work.
While half of these LibDem voters do not currently support the party, the proportion believing the party has made a positive difference is between a fifth and a quarter on most issues, and presumably the party does want to try to get some of its lost voters back too.
So these findings seem certain to harden party opinion against Nick Clegg's opposition to projecting a distinctive LibDem contribution - speaking openly about the yellow and blue influences within the Coalition - rather than seeking joint ownership of everything the Coalition does.
The leader does not have the support in his Parliamentary Party to continue that argument, and we can expect to see a continued shift in how LibDems seek to argue that their presence in the Coalition is making a difference.