U.S. Sens. Richard Blumenthal, D-Conn., and Chris Murphy, D-Conn., on Thursday voted against a waiver that would exempt retired Marine Corps Gen. James Mattis from the required seven-year waiting period for retired military personnel to serve as secretary of defense.

The senators explained that while they think Mattis is the right person for the job, they voted no to underscore the importance of civilian control over the military.

The Senate voted 81 to 17 in favor of the waiver. The House is expected to vote on it Friday.

Blumenthal was one of only three members of the Senate Armed Services Committee to oppose the waiver for Mattis, who left the Marine Corps in 2013. He defended his vote, saying it was to make a point about the "paramount importance" of keeping the military under civilian control, not because he doesn't like Mattis for the job.

"The purpose of the no vote was to say to (President-elect) Donald Trump, you cannot assume that any general or member of the military can be appointed next time around," Blumenthal said.

However, Blumenthal said he would vote to confirm Mattis for the position, provided the waiver is approved.

"If there were ever a case for an exception to the rule, it's General Mattis," Blumenthal said.

Murphy's office released a statement from the senator explaining his no vote.

"General Mattis has dedicated his life to serving his country, and for that I'm incredibly grateful. But I remain deeply troubled that we would break our country's longstanding practice — enshrined in law for good reason — of civilian control of the military. That is a precedent I think is important to stand up for, which is why I voted against the waiver today," Murphy said.

Mattis spent several hours before Senate lawmakers Thursday fielding questions on far-ranging issues such as cybersecurity and women in the military as part of his confirmation hearing. During the hearing, Mattis expressed his support for submarine programs relevant to southeastern Connecticut.

In 2011, the production of Virginia-class attack submarines, which Electric Boat builds under a partnership with Newport News Shipbuilding, doubled to two-a-year. When asked by Blumenthal whether he was committed to continuing the two-a-year rate, Mattis replied, "absolutely, sir."

Mattis also said he supported the continuation of the Columbia-class program, the development of a new class of ballistic missile submarines, which will be built mainly by Electric Boat.

j.bergman@theday.com