Blue State Digital, the consultancy behind Obama's online success will work with The Hope Not Hate campaign.
The campaign was founded by Searchlight, an anti-British National Party (BNP) organisation.
The web strategists will help Searchlight work to stop the BNP winning a seat in the European election. They have already invited thousands of people to join the campaign online.
The company is working on providing tools for Hope Not Hate's new website and will be developing messaging, emailing and fundraising campaigns.
Blue State Digital, which has offices in New York, Washington, and Boston, opened a London office in December 2008. The office is run by London director Matthew McGregor, who has worked for political campaigns including Livingstone's 2008 mayoral bid.
Photo: copyright Barack Obama