Forty-eight Labour rebels – including Hartlepool MP Iain Wright - have defied the party leadership to vote against the Government’s welfare reforms.
Mr Morris was among the MPs to ignore interim leader Harriet Harman’s call for them to abstain in the Commons second reading vote on the Welfare Reform and Work Bill.
Last night, on Monday, July 20, Mr Morris tweeted: “I know where I stand and have just voted for the people of #EastDurham and against Conservative attacks on welfare. I know where I stand and have just voted for the people of #EastDurham and against Conservative attacks on welfare.”
All Sunderland MPs remained loyal to Labour orders and abstained.
The scale of the rebellion could have been even greater if two leadership hopefuls Andy Burnham and Yvette Cooper - who had both criticised Ms Harman over the plan - had not fallen into line.
In senior Labour circles, there was relief that no shadow ministers had joined the revolt, but the Tories said it showed Labour had not learned from their general election defeat.
Mr Burnham meanwhile made clear that he could continue to lead the fight against the Government’s plans if he gained the leadership.
A Labour Party spokesman sought to play down the rebellion insisting that it was “no big surprise”.
“Harriet was clear in the position - that we would abstain - and the majority of Labour MPs did so. However, we always knew that there would be a certain number of people who took a different view,” the spokesman said.
However Work and Pensions Secretary Iain Duncan Smith said that with around a fifth of the parliamentary party voting against the reforms, it was clear Labour had not changed.
“Nearly 50 Labour MPs have defied their leadership and opposed our welfare reforms which will move our country from a low wage, high tax and high welfare economy to a higher wage, lower tax and lower welfare society,” he said.
“It’s clear that Labour are still the same old anti-worker party - just offering more welfare, more borrowing and more taxes.”
Ms Harman had hoped to use the issue to show that the party had listened to voters’ concerns about the high cost of welfare to the taxpayer, but the more triggered a furious reaction across the party.
Earlier Mr Burnham issued a letter to Labour MPs explaining why he had decided to vote with the leadership after Ms Harman tabled a “reasoned amendment” which would have denied the Bill a second reading, although he remained deeply unhappy with the legislation.
“Collective responsibility is important and it is what I would expect as leader of our party. It is why I will be voting for our reasoned amendment and, if it is defeated, abstaining on the Bill,” he said.
“But I can reassure you that this is only the beginning of a major fight with the Tories. I am determined that we will fight this regressive Bill line by line, word by word in Committee.
“If the Government do not make the major changes during committee stage, then, as leader, I will oppose this Bill at third reading.”
SNP employment spokeswoman Hannah Bardell said Labour would pay the price for refusing to oppose the Bill at next year’s elections to the Scottish parliament.
“ “Labour had the perfect opportunity to join the SNP in a progressive coalition to oppose the Tories - but with some honourable exceptions they sat on their hands,” she said.
“This disgraceful stance will haunt Labour through next year’s Scottish Parliament election and far beyond.”
The Bill was given a second reading by 308 to 124, a Government majority of 184.
Labour former Cabinet minister David Blunkett said the party was suffering “emotional trauma”.
He told the BBC Radio 4 Today programme: “I think the Labour Party, understandably, is in emotional trauma. It’s bound to be after the loss in May and the bewilderment about where we go from here.
“What we are not doing, of course, is debating enough about where we go from here. So, last night, once again, focused on us being divided rather than what the Tories are doing, a lot of which is unacceptable.”
The Bill includes a future limit on tax credits to two children per household, a move that was a “difficult” issue for the Labour Party, Mr Blunkett added.
Couples expect to make “logical, rational decisions” about whether they can afford a larger family rather then expecting the state to “pick the bill up”, the former work and pensions secretary said.
“That is a quite difficult argument for the Labour Party. It’s difficult because we don’t want to put children who are with us, or will be in the future, in a position of poverty but we have to put adults in a position of responsibility,” he added.
Mr Corbyn denied he was fuelling a split in the Labour Party.
He told Today: “No. What I have done, along with 47 other colleagues, is voted against the Government’s welfare Bill because of the effect it will have on children of large families because of the effect of the benefit cap, particularly in high-rent inner city areas.”
The revolt is the largest rebellion within Labour ranks since December 2013, according to Nottingham University’s Professor Philip Cowley.
Prof Cowley, an expert on parliamentary behaviour, said that only nine rebellions in the last 10 years had been larger than the welfare revolt - one under Ed Miliband and eight during Tony Blair’s premiership.
“Compared to Blair’s rebellions over Trident or the Education and Inspections Bill, last night looks pretty mild,” he said.
But he added that there were now fewer Labour MPs than under Mr Blair and “splits are usually easier to dodge in opposition”.