The calls for Moore's dismissal continue
Veteran backbencher Tam Dalyell, Islington North MP, Jeremy Corbyn, and the Shropshire MP Paul Marsden all voted with the Tories.
Ms Moore, who is Transport Secretary Stephen Byers' special adviser, sparked anger by suggesting in an e-mail sent on 11 September that the US terror attacks made it a good time to "bury" bad news stories.
The motion calling for Ms Moore to be sacked was easily defeated by 340 votes to 167, a government majority of 173.
And attacking the decision of Mr Byers not to dismiss his adviser, Ms May continued: "Is it not the case that he clings to Jo Moore because if she goes then he knows he is next in line?"
'Clinging to jobs'
The episode typified the government's culture where whatever the issue, spin mattered more than substance, she said.
Mr Byers hit back at the attack, saying of Ms May's speech: "What we witnessed in her contribution was spin around allegations that have no substance."
The minister repeated Tony Blair's stance that the email was "horrible, stupid and wrong" but that the right way to deal with Ms Moore was through the official disciplinary procedure.
Mr Byers moved to rebut specific allegations levelled against the government.
There was no attempt to rush out "bad news" stories in the aftermath of the 11 September attacks, he insisted.
He denied too that a civil servant had been moved because he refused to take part in a "dirty tricks" campaign against London transport commissioner Bob Kiley.
Instead, it had always be envisaged that Transport Department communications director Alun Evans would return to his job.
'No dirty tricks'
Mr Byers did say he had thought the public should know that one of Mr Kiley's assistants had proposed changes to an independent report on the government's plans for the London Underground.
And he accused the Conservatives of ignoring the real issues of substance, such as government plans for Railtrack, the 10 year transport plan, and regeneration proposals.
Liberal Democrat transport spokesman Don Foster condemned Ms Moore's actions but questioned the Tories' priorities in raising it in the midst of the international crisis.
Rather than calling for Ms Moore to be sacked, he pressed for an investigation into other parts of her work and had no doubt that would lead to her dismissal.
"While Jo Moore's e-mail plumbs new depths, this government has taken spin and manipulation to new heights," Mr Foster continued.
Labour MP Tam Dalyell said Ms Moore's mistake more a "moral lapse" than a technical error of judgement.
"I fail to understand the prime minister's inability to recognise that Ms Moore's continued employment in this capacity sullies his government," he said.
Labour votes
That prompted Transport Minister John Spellar to accuse his party colleague of "getting matters grossly out of proportion".
Labour MP Paul Marsden, who went public over his clash with Chief Whip Hilary Armstrong over his opposition to bombing in Afghanistan, also threatened to vote with the Tories.
He said ministers should "stop defending the indefensible" and sack Ms Moore.
But other Labour members came to the defence of Mr Byers in the Commons.
Former Home Office Minister Mike O'Brien said the e-mail was stupid but accused the Tories of displaying "sheer hypocrisy" in their attacks.
They had shown they were out of touch by devoting an entire debate to the issue during the international crisis, he argued.
The government's amendment branding Ms Moore's e-mail "horrible, wrong and stupid," but noting that she had been dealt with under the disciplinary procedures was passed by 342 to 205 votes, a majority of 137.