The last thing the NHS needs are the quack remedies of a charlatan whose real intention is to kill the patient

Charles Kennedy

The Lib Dem leader will argue his party have "repeatedly struck Labour's raw nerve" by taking on the government's healthcare record.

Ahead of the speech, Mr Kennedy said he would raise income tax to pay for more investment in health and education.

Those comments come despite Mr Kennedy recently suggesting the Lib Dems could be a low tax party in the right economic conditions.

Conservative leader Iain Duncan Smith has said he plans to set up a special unit inside Tory headquarters to combat the Lib Dem threat.

And Labour Party chairman Charles Clarke has branded the Lib Dems opportunists "just throwing stones when things go wrong".

Job threats

Mr Kennedy is again to outline his ambition to become the "effective opposition" and hopes his party will be able to overtake the Tories at the next general election.

In his speech, Mr Kennedy will say: "I give Tory MPs due warning. We're coming after you. Many of you are holding onto your political careers."

"Virginia Bottomley, Oliver Letwin, David Davis, Nigel Waterson, David Heathcoat-Amory and Theresa May would all lose their seats to Liberal Democrats on a swing of less then 4%."

Waterson: Relaxed about Lib Dem threats

Those words did not impress Eastbourne MP Nigel Waterson, who won a 2,154 majority over his Lib Dem rival last year.

Mr Waterson told BBC News Online: We have heard all this before from the Liberal Democrats but since at the election I ensured my majority went up, I'm pretty relaxed about this sound and fury."

The Tory MP argued the Lib Dems would stop "toadying" up to Labour if they were serious about becoming an effective opposition.

Mr Kennedy will accuse Conservative leader Iain Duncan Smith of making "sweeping condemnations" of the NHS.

"They inflict little damage on the Government but a great deal on the morale of the doctors and nurses who work in the service," he is expected to say.

"Of course the NHS is currently ailing. But the last thing it needs are the quack remedies of a charlatan whose real intention is to kill the patient."

That criticism echoes Tony Blair's attack on the Conservatives, although Mr Duncan Smith has argued he is simply standing up for those who have complaints and wants to make the system work.

Tax review

Liberal Democrat policy is currently under review, the initial results of which will be unveiled next month.

In a recent interview with BBC News Online, party chairman Mark Oaten branded the pledge to put a penny on income tax to fund education policy as "tired, out of date ... crude and simplistic".

Mr Kennedy told BBC Radio 4's Westminster Hour programme on Sunday that Mr Oaten was right to point out the policy had been used for two election and the party did need to think afresh.

"We cannot sit back, particularly in our political position and be complacent," said Mr Kennedy, who has ended formal cooperation with Labour.

The Lib Dem leader said his party favoured a "transparent tax policy", having previously pressed for the extra penny on income tax and a 50% tax rate for top earners.