A new poll by Survation has shown that UKIP has built on its breakthrough at the Eastleigh by-election last year, where it came a close runner-up to the Liberal Democrats.
Latest polling shows that in a general election voters in the seat would now return a UKIP MP.
The polling, the latest in a series conducted on behalf of UKIP donor Alan Bown, represents the first time that UKIP has been shown in first place for a parliamentary election.
At last year's by-election UKIP's Diane James pushed her Liberal Democrat opponent to the wire and she is expected to represent the party again in the general election next year. Survation have found that UKIP are now in first place in the seat with 32% support, with the Conservatives now in second place on 28%, the Lib Dems third on 27% and Labour in fourth on 12%.
UKIP communications director Patrick O'Flynn said: "This is a stunningly good poll for UKIP and great reward for all the effort that UKIP members have put into raising the party's profile in Eastleigh since the by-election last year.
"We said at the time that we were not going to walk away and felt that this was the start of a long-term relationship between UKIP and Eastleigh and this poll shows we are on course to make that a reality.
"It is yet another indication that UKIP is on course not only to do well in European and local elections next month, but that we also have a very good chance of winning seats in the House of Commons next year."