Lib Dems are focusing on Mr Howard's seat

And he said that if Mr Howard's bid to become leader of the Tory Party is successful it will only fuel Lib Dem efforts to remove him as MP for Folkestone and Hythe.

But the claim was dismissed as "a load of nonsense" by a Conservative spokesman.

He said: "The Liberal Democrats are not fit to be an opposition let alone in government."

At the last election Mr Howard's majority fell from 6,332 to 5,907.

Double defence?

Next time round the Lib Dems would need a 6.5% swing to beat him.

Liberal Democrat chief executive Chris Rennard said: "The election of Michael Howard as Conservative Party leader makes it even more likely that the Liberal Democrats will take the seat at the next election.

"He will be undermined by having to defend the pre-1997 Conservative Party as well as the current Conservative Party."

Lord Rennard said his party needed only one in three or four Labour votes to win in Folkestone, without taking a single Conservative vote.

The Lib Dems are also planning to target other senior Tory figures at the next election.

Home affairs spokesman Oliver Letwin is seen by the party as the most vulnerable to a Lib Dem challenge - at the last election his majority was cut to 1,414 from 1,840.

A swing of 1.5% to the Lib Dems would see them taking his West Dorset constituency.

Also vulnerable are David Davis - who opted not run for the leadership in favour of Mr Howard - and Tory chairman Theresa May.

Help

The Lib Dem strategy was most famously deployed by the Lib Dems in 1992 when they managed to win Chris Patten's Bath seat.

And the party spokesman said Mr Howard becoming leader would help their efforts to win his constituency.

Mr Davis - who is shadow deputy prime minister - had his majority reduced from 7,514 to 1,903 at the 2001 general election.

In order to win his Haltemprice and Howden constituency the Lib Dems need a 2.2% swing.

Also in 2001, Mrs May saw her majority in Maidenhead slashed from 11,981 to 3,284.

Lib Dems need a swing of 3.8% to unseat her.

Shadow cabinet colleague Tim Collins is also vulnerable to a Lib Dem challenge, as is ex-health secretary Virginia Bottomley.