Conyers’ nominating petitions were insufficient, Wayne County Clerk Kathy Garrett said in a statement.
It follows her report last week finding Conyers more than 400 signatures short of 1,000 needed. Garrett said Tuesday that he had 592 valid signatures after challenges.
The 84-year-old Detroit Democrat was at risk because officials believe several people who signed his petitions do not appear to have been registered voters or had registered too late.
Conyers has three days to appeal Garrett’s ruling to the Michigan Secretary of State.
Federal court actions, meanwhile, are taking aim at the requirement that petition collectors be registered voters. The ACLU has filed suit to change state law. If neither happens, Conyers can run as a write-in. If he wins the primary as a write-in, he would qualify for the general election ballot.
Messages were left with Conyers’ attorney and his primary challenger, the Rev. Horace Sheffield III.
“It is a very unfortunate circumstance that an issue with a circulator of a petition would disqualify the signature of valid registered voter,” Garrett said in a statement. “However, I am bound by the current laws and statutes of the state of Michigan that set forth very specific and narrow instructions regarding candidate petitions.”
Conyers was elected to the U.S. House in 1964 after winning the Democratic primary by 108 votes.
Since then, he routinely has won re-election — often with more than 80 percent of the vote — and became the senior member of the Congressional Black Caucus, which he helped found.
Conyers was among six Black House members when he was first elected, beginning more than 40 years of ballot box dominance over most opponents.
He had represented Michigan’s 14th district for decades but moved over to the 13th district in 2012 after Republicans redrew boundaries. At age 83, he still won re-election to a 25th term with 83 percent of the vote.
Conyers got 92 percent of the vote in a 2008 re-election run.
His closest call came in the 2010 general election. That year Conyers received 77 percent of the vote. It came at a time Republicans swept offices across the state, including Rick Snyder’s election as governor. The election also came just two months after Conyers’ wife reported to prison to begin a three-year sentence for corruption.