AON have sponsored the club’s training kit over the past eight years, but their contract is due to expire at the end of June.
Myprotein, who are owned by The Hut Group (THG), were on course to become the new sponsors on a 10-year contract worth £200 million.
However, the Cheshire-based company have now pulled out of the deal amid the anti-Glazers fan protests in recent weeks.
There have been calls from some fans to boycott the club’s commercial partners in protest against the ownership of the Glazers.
THG believe they could be targeted as a local business and have decided to withdraw from the proposed contract.
There has been severe criticism from the fans towards the Glazers ever since United’s involvement in the European Super League formation.
The club quickly pulled out of the breakaway league, but many supporters are desperate to see the owners end their association with the club.
Joel Glazer recently wrote in the Fans’ Forum confirming an increased investment to strengthen the bond with the club’s faithful.
It remains to be seen whether the failure to secure a new training kit deal has any impact on the club’s summer transfer business.
AON, who are also the sponsors of the club’s Carrington training centre, could be handed an extension after the deal with THG fell through.