General Election: polls show Labour and Tories still deadlocked
Voting is under way in the most uncertain General Election for decades, with a final batch of opinion polls showing the two main parties still neck-and-neck.
Ipsos MORI in the Evening Standard puts the Conservatives on 36% and Labour on 35% while the Ashcroft National Poll has the two parties tied on 33%.
With all the indications that the country is heading for another hung parliament, it is still unclear where the balance of power will lie after voting closes at 10pm.
Both the latest opinion polls have Ukip on 11%, with Ipsos MORI putting the Liberal Democrats on 8% while the Ashcroft National Poll has them on 10%.
With so much at stake, party leaders were out early to cast their votes.
David Cameron arrived with wife Samantha at a polling station in his Witney constituency in Oxfordshire, while Ed Miliband and his wife Justine voted in his Doncaster North seat in the contest which will decide which of the two men will enter No 10.
Ukip's Nigel Farage cast his vote in his Kent constituency of Thanet South knowing that his political future is on the line having promised to step down as party leader if he is not elected.
In contrast, Nicola Sturgeon - who is not standing for Westminster - was out voting in Glasgow East, assured of her position and confident of a nationalist surge that will see the SNP wield unprecedented influence in the UK Parliament.
Last out after his Land's End to John O'Groat's campaign marathon was Lib Dem leader Nick Clegg who was voting with wife Miriam in his Sheffield Hallam constituency.
Ahead of polling, Mr Cameron said the way voters cast their ballots would "define a generation" and appealed for more time to build a better Britain, warning a Labour government would be "held to ransom" by Scottish nationalists.
But Mr Miliband accused him of hiding the truth about deep spending cuts that posed a "real and present danger" to families' finances, and urged people to bring an end to "five years of unfairness, five years of failure".
In one of the biggest pre-election polls, a YouGov survey of 10,000 voters for The Sun had the main parties on 34% each - but with a significant 17% saying they were yet to make up their minds - a figure put as high as 25% in a ComRes poll for ITV and the Daily Mail.
In the past such a tie would have been enough to propel Mr Miliband into Downing Street but an SNP surge in Scotland threatens to rob Labour of dozens of its traditional strongholds north of the border and the chance to govern alone.
A YouGov poll in Scotland for The Times shows Ms Sturgeon's party - with which Mr Miliband has ruled out any formal deal - enjoying 48% of support to Labour's 28%, putting several key figures including Scottish Labour leader Jim Murphy in peril of losing their seats.
Ms Sturgeon said her party was "within touching distance" of a majority of Scottish seats at Westminster for the first time and being able to make sure "the voice of Scotland is going to be heard more loudly at Westminster than it has ever been heard before".
She has appealed to Labour to join forces to "lock out" the Conservatives but warned her MPs would vote down a future Labour budget if it failed to end "Tory austerity" - a threat seized on by the Tories as a central theme of its campaign.
Mr Clegg, who faces a fight to hold on to his own Sheffield Hallam seat, urged voters to stick with the Liberal Democrats as the only party able to provide a "stable" influence on a Tory or Labour administration.
He said his party's performance will be the "surprise story" of polling day, dismissing predictions of an electoral mauling that has left key figures such as Cabinet minister Danny Alexander vulnerable to a collapse in support after five year in coalition with the Conservatives.
Mr Farage predicted many undecideds would swing behind the Eurosceptic party as it seeks to translate regular third places in national polls into an influential Commons presence in any post-election negotiations.
"We have a feeling there are lots of people out there who are shy Ukippers who don't tell the opinion pollsters how they will vote," he told an eve-of-poll rally, adding that he was looking forward to the established parties waking up tomorrow with a "huge hangover".
The Green Party will also hope to increase its parliamentary presence, heavily targeting three seats in a push to underline the increasingly fractured political make-up of the electorate.
Polling stations will be open until 10pm in what will be the busiest General Election day since 1979, with nearly 10,000 council seats also up for grabs.
There are contests for 290 councils and six mayors in England.