The House Judiciary Committee announced Thursday that it had served former Trump campaign manager Corey Lewandowski with a subpoena to testify before Congress next month.

Lewandowski has been reportedly considering a Senate run in New Hampshire and is expected to make an appearance at a Trump rally in the state on Thursday night. The House panel's announcement came hours after Trump told a local radio station his former aide would be "a great senator." A Democratic committee source insisted the announcement was not planned to coincide with the Trump event.

The committee also issued a subpoena to former White House deputy chief of staff for policy Rick Dearborn. By an NBC News count, the committee has issued seven subpoenas so far this year.

In a statement, House Judiciary Chair Jerrold Nadler, D-N.Y., said his committee was summoning the two former Trump aides to testify publicly on Sept. 17. The committee had voted to authorize the subpoenas in July.

"These witnesses were involved in President Trump’s extensive efforts to obstruct the Special Counsel’s investigation," the committee said on Thursday.

Nadler said he expects their testimony "will help the Committee determine whether to recommend articles of impeachment against the President or other Article 1 remedies."

"Corey Lewandowski and Rick Dearborn were prominently featured in the Special Counsel’s description of President Trump’s efforts to obstruct justice by directing then-White House Counsel Don McGahn to fire the Special Counsel, and then by ordering him to lie about it,” Nadler said.

The Mueller report said Trump had asked Lewandowski to convince then-Attorney General Jeff Sessions to un-recuse himself from the Justice Department's investigation into Russian election interference, and publicly say that the president had not done anything wrong. Sessions recused himself in March 2017 for the probe following reports that he met with the Russian ambassador during the 2016 election.

Lewandowski told Mueller he didn't pass the message on to Sessions, and tried to have Dearborn do it. Dearborn did not, the report said.

A lawyer representing Lewandowski addressed the subpoena in a statement on Thursday.

"Mr. Lewandowski has voluntarily appeared before and cooperated with Congress three times, answering questions for hours. He also has spoken for hours with the Special Counsel’s office. In light of this, it is fair to ask what could be gained from requiring him to appear yet again."

A spokesperson for Republicans on the Judiciary Committee criticized the subpoenas as a "waste" of "time and taxpayer dollars."

“Special Counsel Mueller has already testified about his full report and to the fact that his investigation was not hindered in any way," the spokesperson said. "Moreover, our committee has had access to the FBI’s interview summaries on these individuals for months, so these subpoenas—like the one to Hope Hicks—only waste more time and taxpayer dollars as Democrats demand information we already have."

Trump fired Lewandowski as his campaign manager after six tumultuous months on the job, but the two have remained close and he often travels with Trump on Air Force One for his political rallies.