While voters remain skeptical about the intention behind any delay, overall they support pushing back Brexit day | Dan Kitwood/Getty Images EXCLUSIVE POLL Public backs Brexit extension — but only if it’s short Support for no-deal Brexit has fallen while support for May’s deal and a second referendum are up.

LONDON — U.K. voters support a delay to Brexit, but only if it lasts no longer than three months, according to an exclusive POLITICO-Hanbury poll published ahead of a crucial showdown in the British parliament over the next steps in the Brexit process.

While voters remain skeptical about the intention behind any delay, overall they support pushing back Brexit day (with 47 percent in favor to 26 percent opposed) if it is needed to continue the exit negotiations or to ratify the deal. But support for an extension lasting any longer than three months drops dramatically, according to the survey of 2,006 adults.

In parliament Tuesday, Theresa May opened the door to a potential Brexit delay. She said she would request a "short, time-limited extension" of the Article 50 negotiating period from the EU if the deal she negotiates with Brussels is rejected again by the House of Commons in a vote before March 12, and if MPs reject a no-deal scenario. But the prime minister said a delay is not her preferred option and she is working to achieve a deal that parliament could back.

While her deal is still unpopular in the country, there are tentative signs that people are coming round to it, according to the poll, which was conducted between February 22 and 25. Overall, 30 percent said it should be approved by MPs, while 37 percent said it should not. But this is an improvement from when the agreement was struck with Brussels in November, when just 28 percent wanted MPs to approve the deal and 45 percent did not.

However, if legally binding changes to the backstop — or a permanent customs union — are agreed with Brussels, public support for the deal sharply increases. No-deal as an option, meanwhile, is falling in popularity based on the last two POLITICO-Hanbury polls.

Any extension that lasts longer than three months is seen as unacceptable.

The findings will be jumped on by those MPs in parliament who are continuing to push for a negotiated withdrawal from the EU despite opposition from Brexiteer and Remain MPs. It may also help to convince those close to May, many of whom are increasingly pessimistic about delivering Brexit while maintaining Conservative Party unity, that the public has not — yet — lost patience with the prime minister’s delaying tactics and obfuscation.

According to the poll, 47 percent of respondents support or strongly support an extension of the Article 50 negotiating period, compared with 26 percent who oppose or strongly oppose such a delay.

But to maintain public support, any extension must be short. Forty-seven percent say a one month extension would be acceptable, compared with 32 percent who say it would not. This falls to 42 percent support for a three-month extension, compared with 40 percent who are opposed.

Conservative Party voters who backed Brexit in the referendum are strongly opposed to an extension though, with 51 percent opposed and 33 percent in favor. Twenty percent would find it acceptable to extend Article 50 in order to hold a second referendum or a general election, compared with 74 percent that find this unacceptable. And 27 percent would find it acceptable to extend Article 50 to prevent no-deal, compared with 63 percent who say that would be acceptable.

At the despatch box in the House of Commons Tuesday, the prime minister said any extension of Article 50 could not last beyond the end of June to ensure the U.K. does not have to take part in the European Parliament’s election. This would amount to a three-month extension.

Any extension that lasts longer than three months is seen as unacceptable. Just a third of voters — 33 percent — find a six-month extension acceptable, compared with 48 percent who say it would not be. Even fewer — 23 percent — say they would find a two-year extension acceptable, compared with 60 percent who say it is unacceptable.

The nationally weighted survey suggests the public would support an extension for two main reasons: to pass the necessary laws to leave with a deal — 47 percent of people find this an acceptable reason — or to continue the negotiations. Just under half — 49 percent — of those surveyed said delaying to carry on the exit talks is valid, compared with 31 percent who said it is not.

The least acceptable reason to extend Article 50, according to the poll, is to hold a general election or second referendum, although even this has public support. Overall, 37 percent say this would be unacceptable, compared with 45 percent who said a delay to allow another round of voting would be acceptable, either in a straight referendum or parliamentary election.

May could make a deal more palatable to the public by making changes to it, but unsurprisingly, those potential changes appeal to different groups of voters.

If May wins “legally binding changes” to the backstop, support for the deal jumps to 37 percent of the public, compared with 26 percent who would still oppose it. In this case, some 48 percent of Leavers would support that deal, and 64 percent of Conservative voters would do so.

If the deal included a permanent customs union (central to the opposition Labour Party's policy), 37 percent of the public would support MPs passing the deal, compared with 30 percent who would oppose it. This support would come largely from Labour voters, of which 47 percent would support it, compared with 25 percent who would oppose. However, support among Leave voters would plummet to 29 percent, while 44 percent would oppose.

While support for May’s deal has increased since the last POLITICO-Hanbury poll in November, so too has support for a second referendum, the survey suggests.

Support for a second referendum stands at just 17 percent of the population, but this is nearly double the support from November, when it stood at only 9 percent.

At the same time, support for a no-deal Brexit has decreased. When asked in November, 23 percent of respondents said of the government’s deal that “this is a bad deal and the U.K. should leave without a deal instead.” That has fallen to just 14 percent in the current poll.

This article is part of POLITICO’s premium Brexit service for professionals: Brexit Pro. To test our our expert policy coverage of the implications and next steps per industry, email pro@politico.eu for a complimentary trial.