BRUSSELS (Reuters) - If British Prime Minister Theresa May loses a vote in parliament on her divorce agreement with the European Union next week, EU leaders won’t rip it up and start negotiating again -- but they could help her try to win a second bout.

Britain's Prime Minister Theresa May leaves 10 Downing Street, London, Britain, December 4, 2018. REUTERS/Henry Nicholls

That help, in the form of new clarifications of how the deal would work or perhaps even small tweaks to agreed text, will not convince the massed ranks of May’s opponents, who see the deal as either too much Brexit or too little. But it would be aimed at winning over enough waverers to salvage the accord.

Senior EU diplomats hope Tuesday’s vote will be close and May can return to parliament and win a second vote. In such a case they could consider helping her with “cosmetic” changes to the non-binding political agreement that accompanies the deal.

But even then, the legally binding text itself, which forms the crux of the debate in Britain, would be off limits to renegotiation. And if a ‘no’ vote in the British parliament is overwhelming, May would be on her own.

“Much will depend on the numbers. If she is short of 15, 30 or 40 votes, we could think of a gesture to let her try again,” said one EU official.

Failure in the vote will transform the quarterly EU summit to be held in Brussels next Thursday and Friday into a “Brexit crisis” meeting, officials say -- though the timing may mean it is too soon for May to tell fellow leaders much more than that she has failed at her first attempt and needs more time.

Officials were unanimous in saying the “Pandora’s box” of going back to drafting the legal treaty on Britain’s withdrawal would not be opened.

“There will certainly be no re-negotiation of the withdrawal deal,” a second senior official said.

“The question is what will the Brits do if the deal fails in their parliament. We are ready to support them.”

That could range from giving more time for May to find other ways to convince the parliament, to even helping Britain halt the Brexit process altogether, as many EU leaders have regularly said would be their ultimate preferred option.

Said another EU diplomat: “We could look at doing something cosmetic, relatively quickly. First, we would have to hear from May, see what they want,” said another EU diplomat. “And if she falls short of a hundred votes, it’s probably not doable.”

The EU has said repeatedly since sealing the deal with May last month that it would not renegotiate, and has backed May’s position that the offer is the best and only deal possible.

Some countries, like France, have a particularly rigid line on offering additional concessions to Britain.

The non-binding political declaration has not been the main bone of contention in the British debate, and it is far from clear that tweaking it would change votes in the House of Commons. Still the suggestion that it could be tweaked may be seen as a sign of greater flexibility.

EU diplomats said unless there is a quick fix and a swift and successful second vote in the British parliament, the case would drag on into 2019, increasing pressure on all sides.

They thought it would be too soon for any major moves at the EU’s final summit of the year next week. It might not even be clear by then whether any changes Britain could seek from the EU would lean towards closer ties after Brexit, or the opposite.

“There is no majority for anything,” another EU official said, noting the difficulty of dealing with the May cabinet and the UK parliament, both split in half on Brexit.

EU diplomats said much would also depend on market reaction should the UK parliament vote down the tentative Brexit accord. If the pound comes under heavy pressure, the British parliament might be more likely to vote in favour the second time.

“There is more concern that May might fail at the first attempt. But we still think she will get it through, eventually,” said another EU diplomat dealing with Brexit.