The former 98 Degrees star embarked on an extensive campaign for ResponsibleOhio, a group calling for the legalisation of recreational and medicinal marijuana, by appearing in their videos and posters and heavily promoting the cause on social media.

Lachey was accused of backing the drive because he stands to earn millions of dollars through the farm he co-owns, which would be one of 10 estates in Ohio allowed to service pot dispensaries, but he insisted the move would improve the local economy as a whole.

The singer ramped up his campaign in the days before the ballot, encouraging the Ohio public to vote in favour of legalisation, but a 65 per cent majority opposed the measure.

He took to after the vote to concede defeat, but hinted he will continue to campaign for a change in the law.

"While I may not agree, the people of Ohio have spoken and that's the way it's supposed to work," he tweeted. "Change takes time. #democracy #respect."