The National Football League has enlisted the support of the Christian right to help drum up opposition to a proposal in Congress that would legalise sports betting and reverse sweeping prohibitions on online gambling that were passed last year.

The primary target of the lobbying campaign by the sports league and Focus on the Family, the evangelical group headed by James Dobson, is a proposal introduced this year by Barney Frank, the powerful Democratic lawmaker, that would undo the Unlawful Internet Gambling Enforcement Act of 2006.