John McDonnell has accused David Cameron of telling an "outright lie" to voters on tax credits during the election and warned that the Tories will become the "new Lib Dems" unless they change tack.
The prime minister and George Osborne are under pressure from Labour and several Tories to abandon planned cuts to working tax credits due to kick in next April.
Lib Dem leader Tim Farron today confirmed his party would back a cross-party attempt in the House of Lords to kill off the cuts using a 'fatal motion' next week.
Writing for The Huffington Post UK ahead of a Commons debate today, the shadow chancellor said Cameron had promised on a BBC Question Time election special that he would not cut the benefit.
"When questioned during the live TV debates before the general election about cuts to tax credits, David Cameron told the British people he wasn't going to even touch them. As a result, the Conservatives no doubt won the votes of many people whose tax credits are soon to be cut," he says.
"And we all know now that those votes were won on an outright lie."
He adds: "Because it is this kind of politics that the public can’t stand. It is the same old politics that saw the Lib Dems dumped by the electorate in May.
"The Lib Dems were not forgiven by voters for the false promises that they gave before the 2010 election on tuition fees. And rightly so, the public want politicians who will be honest with them."
"The Tories need to keep their promises on tax credits or face being the new Lib Dems."
Tory MPs concerned about the plans have been urged to join Labour in voting against the measures in the Commons this evening.
It comes as:
- The Treasury took on its Labour and Tory critics by releasing analysis it said showed cuts made since 2010 will save taxpayers £15bn a year.
- Tory sources threatened to suspend the House of Lords or flood it with Conservatives if peers block the cuts.
- Osborne was challenged on Monday evening over the cuts by Tory MPs at the meeting of the backbench 1922 committee.
- A Tory voter's emotional plea on BBC Question Time for the credits not to be cut went viral
London mayor Boris Johnson is among the Conservative MPs who have warned the cuts will be seen as unfair and could damage the party.
In his blog for The Huffington Post UK, McDonnell said Labour "will not tolerate a government trying to mislead people and we will call it out when it does".
"Therefore, faced with a government that will not be straight with the British people before or after an election, Labour will act. Today Labour will pledge that when we return to power, we will reverse these changes, making sure these families are not losing out," he said.
"The Tories might arrogantly hope that voters will forget, but decisions like this define governments. And the 3 million people who have been lied to certainly won’t forgive the Tories for the false promises they made on tax credits in May at the next election.
"Tory MPs should ask themselves, what is more important, tax breaks for the few or keeping your promises to the many? Because we know the answer and if this government doesn't reverse these changes to tax credits, then Labour will."
The independent Institute for Fiscal Studies (IFS) has concluded millions of working families will be left £1,000 a year worse off as a result of Osborne's cuts to tax credits.
Paul Johnson, the think-tank's director, said: "Actually these changes, they’re certainly hitting people further down the income distribution than the changes that were made under the last parliament but the chancellor made quite a big choice in the Budget, he’s decided actually to hit people in work rather harder than people out of work."
Lib Dem leader Tim Farron told The Huffington Post UK that the cuts were "George’s poll tax" and that it was an "aggressive assault on millions of people in Britain".
"Saying you are listening is cold comfort to hard working people who face losing a large part of their pay packet. The Tories promised tax credits were safe during the election, but this was completely untrue," he said.
“It is time for the chancellor to show the leadership he so badly craves and scrap this disastrous policy. George Osborne should learn from his own party’s history, and change his mind on tax credits today, or give up on any desire he has to be prime minister."
Ahead of today's vote, online campaign group 38 Degrees was shared to highlight Cameron's apparent pre-election pledge not to cut tax credits.
On Monday The Huffington Post UK reported Tory threats to suspend the House of Lords should peers block cuts to tax credits, and suggested the Lib Dems would be the biggest losers of any fresh move to reform the unelected second chamber.
But Farron told HuffPost UK today that he was not caving to the threat. "The Lib Dems will keep making the case for Lords reform as we always have, on principle, not on opportunistic gamesmanship," he said.