UKIP Leader Nigel Farage told Chesham and Amersham MP Cheryl Gillan in a live televised today debate many of her constituents were turning to his party because of the Tories' stance on HS2.
Both politicians appeared on today's Daily Politics show on BBC Two, with Conservative Mrs Gillan being joined by members of the Labour party and the Lib Dems to discuss a possible role for UKIP in future coalitions Governments.
Recent opinion polls suggest up to 16 per cent of voters would be prepared to vote for the party - leading to speculation they could be needed to form a coalition with the Lib Dems' popularity waning.
During today's show Mrs Gillan dismissed UKIP were "a bit of a one issue wonder" regarding Europe, to which Mr Farage replied: "We're against HS2, which your party's not, and that's why we're getting so many votes in your constituency."
In replying "I'm with you Nigel" Mrs Gillan reiterated she was against the controversial project, to which the UKIP leader quipped: "There's a new coalition breaking out."
Mrs Gillan said however all the major political parties should sit up and take note of UKIP's rise in popularity.
She said: "They are starting to broaden their base. We've got to take UKIP seriously - I take UKIP very seriously. All parties should take a party that's taken 16 per cent of the poll seriously."
Having earlier spoken of UKIP's stance on Europe, Mrs Gillan added later: "The time has come for us to look at the relationship between the United Kingdom and the European Union. I don't want to see particularly an in/out choice because I don't believe in an empty chair policy in Europe."
Mr Farage stood against House of Commons Speaker John Bercow in the Buckingham constituency at the last General Election but was beaten into third place in the poll.
He has also campaigned in Bucks on a frequent basis after saying his party is the only one that has consistently been opposed to HS2 - a hot political topic in the county, with the line set to cut through the Chilterns Area of Outstanding Natural Beauty if the scheme is given the go-ahead.