A U.S. House ethics committee on Tuesday announced it’s investigating U.S. Rep. Rod Blum, the incumbent Republican in Iowa’s first congressional district, following news reports earlier this year that he failed to disclose his private business on a required form.

The Committee on Ethics for the U.S. House of Representatives said that its top leaders had decided to “extend” a “matter” about Blum. The Office of Congressional Ethics referred the issue to the House committee in July. The office is a nonpartisan, independent entity that reviews allegations of misconduct.

The House committee plans to announce “a course of action” on or before Dec. 17, according to the letter. That’s just over a month after the November election, where Blum faces a challenge by state Democratic Rep. Abby Finkenauer. The district, which covers the northeast part of the state, is considered competitive and one of the Democrats’ best chances to reclaim a majority in the House.

Tuesday’s release from the ethics committee doesn’t offer more specifics, and notes its existence doesn't indicate a violation has occurred. Blum, however, quickly released a statement confirming the inquiry is related to his disclosure form.

Blum accused Finkenauer and other Democrats of waging "a crusade of personal destruction on me and other principled leaders working to drain the swamp in Washington — this is the Swamp fighting back."

"Rather than present solutions, the Democratic elite aim to destroy their opponents' reputations through distortions. In my case they scream 'ETHICS VIOLATION!' over a clerical error on a form," Blum added.

The Associated Press reported in February that Blum didn’t disclose his role in an internet marketing company he formed. A chief of staff in Blum's congressional office was also featured in a testimonial about the company.

Blum, who has repeatedly said the lack of disclosure was an administrative oversight, later amended the form. He reiterated that point in his Tuesday statement and said errors in financial disclosure forms are common.

Blum then criticized the press for reporting about the form.

"Still, the complicit media continues to take its cues from the Democratic party and they work to make mountains out of molehills in order to deliver an election scandal headline," he said.

National Democrats pounced on the Ethics Committee's release.

"Rod Blum promised Iowans that he would drain the swamp, now he’s caught swimming in it," said Rachel Irwin, a spokesperson for the Democratic Congressional Campaign Committee. The DCCC is House Democrat's campaign arm.