Voting gets under way amid drizzle London mayor Boris Johnson and his Labour rival Ken Livingstone were among the first to head for the polling stations under drizzly skies. An eve-of-poll survey for the Evening Standard suggested that Mr Johnson - who gave a confident thumbs-up as he arrived to cast his ballot in north London - was set for victory over Mr Livingstone, by a margin of 53% to 47%. But holding on to City Hall may be the only silver lining on a cloudy day for Prime Minister David Cameron, with voters elsewhere expected to dish out a mid-term bruising to the Conservatives and their Liberal Democrat coalition partners. Conservatives and Liberal Democrats are braced to lose hundreds of the around 5,000 seats at stake on 181 local councils across England, Scotland and Wales. Voters in 10 cities holding referendums on whether to have elected mayors are expected to give a lukewarm response to the idea, which is enthusiastically backed by Mr Cameron, who yesterday said he would like to see "a Boris in every city." And the YouGov poll suggested Labour will pick up three seats in the 25-member London Assembly, becoming the largest party on 11, to the Tories' eight (down three), Lib Dems' two (down one) and Greens' two (unchanged). The UK Independence Party could be heading for its first seats in the Assembly, according to the survey, which predicted the eurosceptic party could secure two. The poll indicated as many as two in 10 Labour supporters may not back Mr Livingstone, despite calls from party figures for them to "hold their noses" and give him their votes. In response, a spokesman for Mr Livingstone said: "Today, Londoners can vote Labour to cut their fares and save themselves on average £1,000, and in doing so ensure that the Conservative Party is not rewarded. Every Labour voter must turn out today or the Tories will get away with it - they will carry on with policies that have led to recession, fare rises and police cuts. Mr Cameron and Labour leader Ed Miliband were also early visitors to polling stations in London, accompanied by wives Samantha and Justine, while Lib Dem leader Nick Clegg cast his ballot alone in Sheffield, as Spanish wife Miriam does not have a vote. Recent opinion polls have shown a clear national lead for Labour - often in double digits - as the Government has wrestled with a month-long string of difficulties. Respected election experts Colin Rallings and Michael Thrasher of Plymouth University say Labour's advantage should translate into a dramatic gain of as many as 700 seats. That number was seized on by Tory Communities Secretary Eric Pickles who said Labour could reach the target "just by turning up" as he attempted to minimise the impact of any heavy defeat. Most of the contested seats were last up for grabs in 2008 - when the Conservatives made significant gains and Labour were hit hard. In turn, Labour tried to downplay expectations, suggesting its hope was for between 300 to 350 gains in England and 100 in Wales - with continued losses to the SNP in Scotland. The Liberal Democrats are braced for a second consecutive year of losses, though they hope to avoid a repeat of the hammering they suffered last year and do not fear coming fourth behind Ukip. Mr Cameron yesterday urged people to focus on local rather than national issues in the wake of a turbulent spell for the coalition. "I recognise it's a difficult time for families, it's a tough time for families," he said. I just hope that people will look at these elections and recognise it's about electing your local council - who is going to keep the council tax down, who's going to provide value for money, who's going to look after your area? Mr Miliband promised Labour would "stand up for the many" rather than the "rich and powerful" he said were the priority of the coalition. "Labour is showing that we can make different choices, decisions which help people through these tough times," he said on the campaign trail. And Deputy Prime Minister Mr Clegg said every Liberal Democrat councillor elected was a "step towards a more liberal country" in a letter to activists lauding the party's town hall record. While many councils will begin counts after the polls close tonight, helping to give a clear picture of the parties' performance, a large number have delayed until tomorrow. A delayed count will also mean a wait to find out the result of the highest-profile contest as Mr Livingstone attempts to seize back the London mayoralty he lost four years ago. The final decision of Londoners is not expected to be known until tomorrow evening. Mr Johnson made a final bid for votes with a video message on YouTube on what he said was "a critical day in the life or our city." Citing plans to create 200,000 jobs and 250,000 apprenticeships and get more police on to the streets, Mr Johnson said he had "the best plan to take London forward over the next four years" and urged Londoners not to "lurch back to the waste and arrogance and divisiveness of the Ken Livingstone years." Mr Livingstone used left-leaning blog Labour List to send an election day message stressing his plans to cut public transport fares. "By spending just a few minutes at the polling station the average fare-payer can make themselves £1,000 better off," said the Labour candidate. There are not many ways you can make £1,000 in less than half an hour. But that is what the average London fare-payer can do from 7am to 10pm today. In a message on Facebook, Ukip leader Nigel Farage urged his party's supporters in London to give their second preference votes to Mr Johnson. "Londoners - please vote Ukip first and Boris second to keep the Socialists out of City Hall - that includes all the others," said Mr Farage. Let's get Ayatollah Livingstone out of London politics once and for all. :: YouGov polled 2,119 Londoners between April 30 and May 2.