Just one in six people in Britain thinks immigration has been good for the country, a major study reveals.
And Britons say the main benefits come from migrants' willingness to do unattractive, low-paid jobs.
The poll, by former Conservative deputy chairman Lord Ashcroft, found support for the government's controversial 'go home' vans that were driven around London had swelled to 79%.
The study of more than 20,000 people found that 60% believed migration was hurting the UK overall.
Ashcroft's research revealed a complex public response to immigration, with many deeply concerned about the perceived problems it causes but also intolerant of racism and appreciative of the benefits immigrants can bring.
Immigrants “claiming benefits and using public services when they have contributed nothing in return” and “increasing pressure on schools and hospitals” are the biggest concerns.
Despite this, many experts believe immigrants are less likely to claim benefits or use the NHS.
And 83% of those surveyed by Ashcroft said they or a relative had been treated in the NHS by someone from overseas.
“Doing jobs that need doing but British people don’t want to do” and being “prepared to work harder for lower pay than British workers” were regarded as the main advantages to immigration.
A major concern was the economy, with 77% believing a dramatic reduction in immigration would reduce pressure on public services and welfare, making it easier for British people to find jobs. Just 23% felt it would harm the economy.
A further 62% said their biggest concern about immigration was foreign nationals claiming benefits and using public services, while just over a third said they or a relative had been denied housing or other public services apparently because of competition from immigrants.
But almost half - 49% - of those polled felt that immigrants often took on jobs that British people were unwilling to do.
When questioned about the recent campaign by the Home Office which involves messages on advertising vans telling illegal immigrants to "Go home or face arrest", 79% of respondents supported the message, but just 17% felt the policy would work.
In the report, which is released on Monday, Lord Ashcroft said the public had a poor view of politicians' understanding about their concerns.
Writing in the Sunday Times, he said: "Many feel that over the past 15 years immigration has been allowed to happen on a scale we cannot cope with, and without public consent being sought or given.
"Whatever people's views of immigration itself, few think any recent government has had any real grasp of it, or that any of the parties does today.
"Most do not feel there is any strategy for dealing with the number of migrants and their successful integration into British society, or for managing the effects on housing, infrastructure, jobs, the NHS, schools or the benefits system."