Kentucky Republican Rep. Geoff Davis unexpectedly resigned from Congress late on Tuesday, citing family concerns.

"Recently, a family health issue has developed that will demand significantly more of my time to assist," Davis said in a statement. "As a result, I cannot continue to effectively fulfill my obligations to both my office and my family. Family must and will come first."

Davis said he submitted his resignation Tuesday to Gov. Steve Beshear and House Speaker John Boehner and that his resignation will be effective at close of business.

Davis had already planned to retire and was not running for re-election in his 4th District, but his resignation will leave an immediate vacancy in Congress and in the representation of his district.

Republican Thomas Massie, who's running against Democrat Bill Adkins to succeed Davis, issued a statement thanking Davis for his service following the news of his resignation.

"My wife, Rhonda, and I admire Congressman Davis' family's commitment to God, family and country and pray for a swift and complete recovery from their family health issue," Massie said.