The Liberal Democrats are the new 'Loony Left' of British politics, according to Iain Duncan Smith.
In a speech to the Carlton Club political dinner at London's Dorchester Hotel, the Tory leader promised a "major campaign" to highlight his contention that Mr Kennedy's party is not a moderate one.
He told his audience that the Liberal Democrats' true face was on display during their campaigning for last week's Brent East by-election, which they won from Labour on a 29% swing.
Mr Duncan Smith said: "On Saturday I made a strong attack on the Liberal Democrats. It wasn't a tactic in response to Brent, but the beginning of a major campaign. A campaign we will take to every doorstep in Britain ... the Liberal Democrats are not moderates.
"In Brent, they campaigned on a platform of anti-Americanism and even higher public spending. At their conference this week, they are voting to abolish the monarchy, ban smacking and impose compulsory sex education for seven year-olds.
"They've moved from weak Left to loony Left. Red Kennedy isn't an alternative to Tony Blair - he's his echo.
"Mr Blair is soft on soft drugs - Mr Kennedy is soft on hard drugs too. He wants higher taxes, weaker asylum rules, fewer burglars in prison and an end to our national currency."