Shadow Chancellor George Osborne called for discipline from Conservative activists on tax as he set out plans for policies to support the family.
This week's Tory conference in Bournemouth has witnessed loud grassroots grumbling over the refusal by Mr Osborne and leader David Cameron to promise upfront tax cuts.
Mr Osborne used his keynote speech to assure the party: "I want lower taxes."
But he warned that Conservative hopes of victory at the General Election expected in 2009 could be dashed if voters fear they will put tax cuts ahead of economic stability or the public services.
He said:"I am not going to write my 2009 Budget in 2006. For the British people are sick of politicians who promise more than they deliver. We will deliver more than we promise."
Mr Osborne had a few morsels to throw to the delegates on tax, including a pledge to end Gordon Brown's practice of "taxation by stealth" and an aspiration to create a "simpler, flatter and fairer" tax system.
And he signalled new assistance for parents, including help on childcare and extended flexible working.
Earlier this week, the conference saw former party chairman Lord Tebbit win cheers by brandishing the 1979 and 1987 manifestos and call for the tax-cutting agenda of Margaret Thatcher's administrations.
And Edward Leigh, a high-profile backbencher, has claimed the Tories could lose votes to parties such as the UK Independence Party if it fails to offer "robust" policies.
Mr Osborne told the conference: "I want lower taxes. Because lower taxes would help Britain. I think we're crazy as a country to be raising our taxes when our competitors are cutting theirs."
But he added: "Surely we must have learned from three election defeats this simple truth - we must win the argument on the economy.
"We will never ever win the argument on tax - or on anything else for that matter - if people fear for one moment that we might endanger the stability of the economy, endanger the low mortgage rates and low inflation families depend on. If we haven't learned that in our long years in opposition then we have learned nothing."
However, Mr Osborne did not rule out tax cuts entirely, adding: "We will share the proceeds of growth between the lower taxes this country needs and the increases in spending on public services every government should provide."