George Osborne is due to defend his Budget, following the government u-turn on welfare cuts, saying it delivers on "social justice and economic security".
But David Cameron defended his Chancellor and said he would be "winding up the Budget debate" on Tuesday insisting that the Conservatives run a "modern, compassionate, one nation" government.
Ahead of a vote to pass the Budget on Tuesday, Osborne is set to echo the the Prime Minister's comments by describing it as one "of a compassionate, one nation Conservative government determined to deliver both social justice and economic security."
"It's a Budget that puts the next generation first," he will say.
He will add that his Budget will lift 1.3 million of the lowest earners out of income tax and deliver improvements to schools whilst supporting businesses, creating jobs and boosting social mobility.
Osborne is also expected to express his sorrow over the resignation of former work and pensions secretary Iain Duncan Smith, who stepped down over "deeply unfair" welfare cuts.
"I’m sorry Iain Duncan Smith chose to leave the Government last week, and want to recognise his achievements in helping to make sure work pays, breaking the old cycles of welfare dependency and ensuring the most vulnerable in our society are protected. That’s work this Government will go on doing," he will say.
On Monday, David Cameron said that Duncan Smith had "much to be proud of in helping the government to reform welfare benefits".
Here is his statement in full:
As Conservatives, we know that those who suffer most when Britain loses control of its public finances and the economy crashes aren’t the best off but the poorest and the most vulnerable.
McDonnell expressed sympathy for Mr Gauke who he said had been left by the chancellor to "defend the indefensible" and called on the Chancellor to withdraw the Budget and "start again".
Liberal Democrat leader Tim Farron lamented "the failure of the chancellor to be here to answer for himself".
But a spokeswoman for David Cameron said that the Chancellor "absolutely" has the full confidence of the Prime Minister.