David Cameron says he hopes to govern for all of the UK
His party made gains in England and Wales, including taking Ed Balls’ seat.
Two senior Labour sources have said that Ed Miliband is expected to stand down later after Labour was all but wiped out by the SNP in Scotland.
The Lib Dems are heading for as few as eight MPs while UKIP leader Nigel Farage failed to win Thanet South.
Mr Farage, who lost to the Conservatives by nearly 2,800 votes in the Kent seat, has said he would step down if he did not make it to Westminster.
A forecast, with 635 of 650 seats declared, is Conservative 329, Labour 234, the Lib Dems eight, the SNP 56, Plaid Cymru three, UKIP one, the Greens one and others 19.
So far, the Conservatives are expected to have won a 37% share of the national vote, Labour 31%, UKIP 13%, the Lib Dems 8%, the SNP 5%, the Green Party 4% and Plaid Cymru 1%
Mr Cameron all but declared victory in a speech after being returned as MP for Witney, in which he set out his intention to press ahead with an in/out referendum on Britain’s membership of the European Union and to complete the Conservatives’ economic plan.