The gamble that Nick Clegg is taking, is that voters will be mature enough to accept this realism and give the party their vote. Unfortunately, democratic politics seldom works in the manner wished of it by party leaders.
For Scotland, the Lib Dems propose to introduce all the Calman Commission recommendations to hand more powers to Holyrood as quickly as possible. More controversially, it proposes to end the Barnett formula and replace it with a needs based version. This would mean Scotland getting less money.
There is no doubt that Barnett is well past its sell-by date. Scrapping it would be popular south of the Border where opinion has hardened against per capita spending figures which appear to show Scotland enjoying an advantage over other hard-pressed areas such as the West Midlands, the north-east of England and the south-west.
But reaching an agreement that does not end up inflaming the very grievance culture Barnett sought to mollify will be difficult. In addition, needs assessments, while having an aura of clinical neutrality, can be fiddled to include elements that some might not see as "needs" at all, or whose cost is inflated to secure greater advantage. The deeper flaw is that such assessments are straight out of central planning and open to all the criticisms: it is cumbersome, bureaucratic, unresponsive to changing circumstances and a product of civil servants and planners with all the shortcomings therein.
Elsewhere the document promises everyone a tax break by exempting the first 10,000 of earnings from income tax and it says it will raise 4 billion by closing tax loopholes for the rich and big corporations. There is a proposal to reduce the cost of public sector pensions and to freeze the pay of public sector high earners.
For all the detail, however, the Lib Dems still struggle with their status as a third party. And while the manifesto does give Clegg some credibility, with his respected finance spokesman Vince Cable permanently beside him in photo calls like a substitute wife, the persona of the leaders and their ability to inspire confidence will be critical in this tough period. Can the public warm to him?
The prospect of a hung parliament, and the Lib Dem leader potentially playing a make or break role in forming a post-election coalition means the party cannot be dismissed as an irrelevant also-ran.