Ex-steelworkers who lost their pensions when their firm went bust say MPs have failed them after a move to set up a "lifeboat" fund was overturned.
Thousands of people took part in pension protests earlier in the year
MPs voted 303 to 253 against Tory changes to the Pensions Bill.
Ministers said they were prepared to move towards providing 90% of core entitlements for the 125,000 people affected - up from 80%.
But ex-Allied Steel and Wire (ASW) workers from Cardiff and Kent said they wanted their full entitlement.
About 1,000 ASW workers lost their jobs and their pensions when the company was declared bankrupt in 2002.
The Conservative proposal was for a "lifeboat" scheme to raise the level of compensation for victims of pension schemes which collapsed between 1997 and 2005.
Pension campaigner Andrew Parr said: "I think the comment in the commons where 'look in the mirror tomorrow morning when you are having a wash and shave and say did I do the right thing today?' [was telling].
"I think most MPs in the House [of Commons] today their consciences will tell them we deserve the pensions that we were promised, and they have not lived up to their conscience today."
Pensions minister Mike O'Brien said the cost of an increase from 80% to 90% could be met by better use of assets still in failed schemes, matched by a further government contribution.
But he had warned that delays to the bill would cause delays to payouts.
Sixteen Labour backbenchers, including former welfare reform minister Frank Field, voted against the Government.
Labour MP Tony Wright, who was one of the Labour rebels, said the government's announcement it would give pensions victims more help was "welcome" but not "a position of justice".
Liberal Democrat pensions spokesman Danny Alexander said there was "real and justifiable anger" on the issue.