If you were in any doubt about how damaging the continued controversy over the NHS bill could be for the Conservatives, look no further than the Guardian/ICM poll out today.

The topline figures are typical: the Tories are on 36 (despite opening up a five point lead in the Guardian's poll last month), Labour are up two on last month at 37, while the Liberal Democrats are at 14. These results mirror those in the Populus/Times poll, also out today, which puts the Tories on 37, Labour on 39, and the Liberal Democrats on 11.

It certainly jumps out that the Tories have lost four percentage points in a single month in the ICM poll, although it looks as if that five-point lead was an outlier. The really interesting findings are on the NHS.

An outright majority of respondents -- 52 per cent -- believe that the health bill should be scrapped. Just 33 per cent believe that at this stage it is better to persevere with the reform, meaning that there is a 19 point margin in favour of axing the bill. This is reasonably consistent across social classes, gender, and regions.

While Conservative voters are more likely to support the bill, worryingly for David Cameron, a third of them (31 per cent) would like it to be scrapped. A significant majority of Liberal Democrats -- 57 per cent -- want it shelved. The issue is set to dominate the party's spring conference next month, for the second year running.

Perhaps this is hardly surprising. Yesterday saw a raft of negative headlines about NHS reform, as Cameron excluded health professionals who oppose the bill from a special Downing Street summit and an angry pensioner berated Andrew Lansley in front of TV cameras. Meanwhile, an e-petition calling for the bill to be dropped has amassed over 150,000 signatures.

Amid this growing opposition to the bill, it appears that the role of the private sector in healthcare is actually becoming more controversial than it used to be. Respondents were reminded that private companies already provide some NHS treatments, but 53 per cent still said that competition of this kind undermines the health service, while just 39 per cent believed it would result in higher standards. When ICM asked a similar question in September 2005, the public was more evenly divided, with 48 per cent endorsing more private involvement and 49 per cent opposing it.

There is growing concern amongst Conservatives that the healthcare bill could seriously undermine their chances at the next election and undo Cameron's hard work on detoxifying the Tory brand. The influential website ConservativeHome called for it to be scrapped earlier this month.

Today's poll appears to confirm that damage to public standing: 40 per cent of respondents said they did not trust the Conservatives "at all" to run the health service (compared with 31 per cent in October 2006, a year into Cameron's leadership). Meanwhile, just 25 per cent said they did not trust Labour "at all", down from 32 per cent in 2006.

As the Prime Minister personally throws his weight behind pushing the legislation through, there is a clear opportunity for Labour to capitalise on this loss of trust. Whether they will successfully turn this into a significant poll lead remains to be seen.