Longtime Michigan U.S. Congressman John Conyers could fail to qualify for the ballot, as a number of petition signatures he submitted have been deemed invalid.

The Detroit Democrat submitted the maximum allowed 2,000 signatures, but the Wayne County Clerk's Office found that just 1,193 are valid and Conyer's Democratic challenger, Horace Sheffield, is contesting another 300 signatures gathered by two circulators who may not have been registered to vote at the time they circulated petitions.

Candidates for the U.S. House in Michigan need a minimum of 1,000 signatures to qualify.

If Sheffield is successful in his challenge, Conyers, who has been a fixture in Congress for 50 years, would be off the ballot.

Wayne County Election Director Delphine Oden says, at this point, the challenges remain unresolved, but once all the challenges have been resolved, the clerk will be able to certify the ballot.

June 6 is the deadline for Secretary of State Ruth Johnson to certify the ballot.