Gordon Brown cleared the final hurdle of the race to complete Britain’s ratification of the EU reform treaty last night after a last-ditch effort to delay it failed in the House of Lords.

Protesters had to be cleared from the public gallery as the six-month parliamentary passage of the Bill to ratify the Lisbon treaty reached a dramatic conclusion. Opponents had sought to delay its completion by four months in the wake of the Irish referendum, arguing that the “no” vote had dealt the treaty a fatal blow.

But the delaying motion, tabled by the Tories, was heavily defeated after Liberal Democrats voted with Labour peers, clearing the way for its Royal Assent, expected today.

Earlier Mr Brown and David Miliband, the Foreign Secretary, denied that they intended to use Britain’s ratification to “bully” the Irish Government at today’s Brussels summit.

David Cameron challenged the Prime Minister to rule out any “arrogant and high-handed” attempt to force Dublin to hold a second vote. “It would be ridiculous to ask the Irish to vote twice, when we haven’t even been allowed to vote once,” the Tory leader said. “I’ve seen more spine and leadership from a bunch of jellyfish. Why don’t you give some leadership, tell us what you think and kill this treaty today?” he demanded at Prime Minister’s Questions. In reply, Mr Brown sought to portray the Conservatives as “viscerally anti-European” and he accused Mr Cameron of being led by his backbenchers.

He said it was right to have respect for the Irish decision but added: “We should have respect for the other countries that are processing the treaty and ratifying the treaty as well. And perhaps we should also have respect for this House, which has also voted for ratification of the treaty.”

Later, in a separate Commons debate on the EU, Mr Miliband argued that any delay to British ratification would weaken its negotiating hand at a crucial juncture. “If we halt ratification, the UK will be leaving itself in limbo, unable to state clearly its own position,” he said. “To choose limbo would be a crazy way to seek influence in the EU. Issues such as climate change and energy security, migration and terrorism won’t stand still while we wring our hands about the EU’s internal structures.”

But William Hague, the Shadow Foreign Secretary, said that the Government had been “caught out and exposed” by Ireland when it had consulted its own people. “Now, faced with the logical choice of abandoning the treaty and saying so or conniving in some way of getting the Irish to vote again, they go along with what is necessary for the latter while denying they are doing so rather than show the merest sign of courage,” he said.

Sir Malcolm Rifkind, the former Tory Foreign Secretary, said that the EU had reached a “watershed” and that there was an inevitability of an “à la carte” Europe where member states accepted certain core responsibilities but could opt out of further integration.

The European Union (Amendment) Bill cleared the Commons in March after 14 days of debate. During the course of that battle, 29 Labour rebels backed a failed attempt to force the Government to hold a referendum.

The last hopes of delaying or defeating parliamentary ratification rested with the Lords, where Lord Howell of Guildford, the Tories’ foreign affairs spokesman, had tabled a motion delaying its completion to October. The debate was interrupted by protests from pro-referendum campaigners.

Lord Howell said it was “crystal-clear” that Parliament would have to take account of any changes to the legislation that might be required as a result of the Irish verdict. It would be “very unwise to push the Bill through now”. He was supported by Lord Owen, former leader of the Social Democratic Party, and Lord King of Bridgwater, the former Tory Defence Secretary, who called it an insult to Parliament to expect it to ratify “a corpse”. But Lord Richard, the former Cabinet Minister and ex-European commissioner, opposing the move, said: “If we pass this Bill, our position becomes clear. If we don’t, it will remain imprecise. It would be ludicrous now to refrain from completing our job.”

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