(CNN) - Michigan Rep. Thaddeus McCotter may face a re-election hurdle that is not related to anti-incumbency sentiment or his ideological purity.
The Michigan Republican may not be on the ballot.
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"I have been apprised my campaign may have submitted insufficient petition signatures to appear on the August primary ballot as a candidate for the 11th Congressional District's Republican nomination," McCotter said in a statement Friday evening.
The Michigan Secretary of State's Office required congressional candidates to submit 1,000 valid signatures by May 15 to qualify for their party's ballot.
State law dictates those signatures be collected no more than 180 days before the petition is filed, and candidates may submit up to 2,000 signatures to cover any ruled as invalid.
McCotter's statement said his campaign would "review our petition signatures for their sufficiency or insufficiency," and respect "the accuracy and integrity of the Secretary of State's office."
It provided no information as to why the campaign may not have submitted a sufficient number of valid signatures.
McCotter was first elected in 2002 and would be seeking his sixth term this year. He previously served in the state Senate, and in September, ended a short-lived run for the Republican presidential nomination.
The Michigan primary will be held August 7.
- CNN's Robert Yoon and Gregory Wallace contributed to this report