A group of doctors is threatening to stand candidates at the next general election in revenge for the Health and Social Care Bill. The anti-reform medics plan to target at least 50 senior Liberal Democrats and Conservatives with small majorities, running on what Clive Peedell, co-chair of the NHS Consultants’ Association, describes as “the non-party, independent ticket of defending the NHS.”

It would be mere quibbling to point out that 50 candidates standing on a common platform would be a party, not a non-party, nor independent. More salient is that the history of similar movements and independent candidates in general elections offers little encouragement for Dr Peedell and his colleagues. In 1990, a group of GPs established the NHS Supporters Party, with the identical aim of standing 50 parliamentary candidates; the peak of its success was to achieve ninth place in the Mid-Staffordshire by-election of that year, with 102 votes.

Despite their disdain for the established parties, voters are very reluctant to vote for independent candidates, however much they may like the idea in principle. Both the main parties could at least form a government, and will have policies in all areas that have some chance of being implemented. In practice, independent candidates largely serve as receptacles for protest votes.

Recent years offer two notable exceptions: in 2001, Dr Richard Taylor was elected in Wyre Forest on a platform of restoring the Accident & Emergency unit at Kidderminster Hospital, and in 1997 Martin Bell was elected in Tatton on a platform of not being Neil Hamilton. These examples show that for an independent candidate to win, they need an issue that is very local, very specific, and very popular. They also need the connivance of at least one major party—Labour dropped out in Tatton, and the Liberal Democrats did not stand in either seat. None of these conditions are in place for Dr Peedell’s group.

But suppose it defied history and managed to make an impact. What is its potential support, and how could it affect the result of a general election? Earlier this week I conducted a poll to find out. In the standard voting intention we found Labour on 41%, with the Conservatives on 36%, and the Lib Dems on 9%.

Interviewees were then told: “Some doctors opposed to the coalition government’s policies on the NHS have suggested they may put up candidates at the next election on a non-party, independent ticket of defending the NHS.” When we asked how they would vote in such a scenario, the NHS candidates came third, with 18%. This included 4% of those who would otherwise have voted Tory—but 15% of Liberal Democrats and fully one fifth of Labour voters. Labour’s five-point margin became a Conservative lead, of 33% to 30%. The Liberal Democrats fell to 7%.

According to UK Polling Report’s “Swingometer,” (which should be taken with a considerable pinch of salt in this case, since we do not know how the NHS candidates’ votes would be distributed), the effect of Dr Peedell’s intervention would be to transform a comfortable outright Labour victory into a hung parliament with the Conservatives just four seats short of a majority.

The poll also found that only 19% supported the health reforms, but this included 51% of Conservatives, as well as 14% of Liberal Democrats. Given the fierce debate, it is worth noting that only 50% said they opposed the plans, 16% said they neither supported nor opposed them, and a further 15% did not know.

This article first appeared on ConservativeHome.com. For further details of the research, please go to www.lordashcroft.com.

Lord Ashcroft is an international businessman, author, and philanthropist. From 2005 to 2010 he was deputy chairman of the Conservative Party.