From BBC News :
Speaking on BBC Radio 4's The World at One, Mr Burnham, who was a critic of the plan to abstain, said he had persuaded Ms Harman to adopt a "compromise" position by putting forward a "reasoned amendment" opposing some of the bill's measures.
That amendment, which would have derailed the legislation, was defeated by 308 votes to 208.
"I still do not believe that that was a strong enough position," Mr Burnham said. "As leader I would have opposed this bill last night."
But he said he was "not prepared to split the party and make the job of opposition even harder".
I think the job of opposition just got a lot harder for a party that doesn't seem to know what it's doing.