An ICM/Guardian poll says the Conservatives, led by David Cameron, have 33 percent support. The Labour Party, led by Prime Minister Gordon Brown, and Liberal Democrats, led by Nick Clegg, are tied with 28 percent each.
The British vote May 6 and to secure a majority in the House of Commons a party must win at least 326 seats out of 650.
The survey questioned 1,026 adults by telephone from April 20 to May 2. No margin of error was given, but in samples that size it is plus or minus 3 percent.
The three candidates address a citizens' forum in London later Monday.