Democrats retained control of the U.S. Senate majority in a number of nail-bitingly close elections in states key to the defense industrial base.

And the election sets up a potential shift at the top of the Senate Armed Services Committee, where Sen. John McCain, the top Republican, faces a party term limit. At least five seats on the committee, four of them Democratic, are now vacant due to retirements or losses.

Departing Democrat James Webb (Va.), a former Navy secretary, will be replaced by former Virginia Gov. Tim Kaine (D). Kaine has pledged to remain strong on defense and to protect a Virginia aircraft carrier from being moved to Florida, and says tax increases should be part of a balanced package of deficit reduction.

Democrat Elizabeth Warren unseated Republican Sen. Scott Brown in Massachusetts, taking control of a state that is home to Raytheon’s headquarters and with a major General Dynamics presence. Brown had led the airland subcommittee on the Senate Armed Services Committee, opening up another leadership spot.

Claire McCaskill (D) edged out challenger Rep. Todd Akin (R) in Missouri. That gives McCaskill, an advocate for Boeing’s F-18 and tougher restrictions on contracting, a stronger position on the committee. Akin’s loss opens a vacancy at the top of the House Armed Services seapower and projection forces subcommittee.

Democrat Chris Murphy (D) replaces Senate security stalwart Joe Lieberman (I) in Connecticut, where United Technologies Corp. remains a powerhouse defense company. Roger Wicker (R-Miss.) holds on to his seat that often focuses on the Gulf Coast’s shipbuilding efforts, gaining in influence on the defense policy panel.

A key hold on the Republican side of the Senate is earmark-crusader Rep. Jeff Flake (Ariz.) in the race to replace the hawkish Jon Kyl (R). But with Flake’s record on government spending, he joins McCain as a potential maverick in the defense-heavy state.

Other notable elections include: Bill Nelson (D), a space industry advocate, who retains his seat in Florida. Meanwhile, Ted Cruz (R-Texas) takes over for the outgoing Sen. Kay Bailey Hutchison (R).

And in Indiana, Joe Donnelly (D) will replace Sen. Richard Lugar (R), the Senate Foreign Relations Committee chairman who was ousted in the primary by Richard Mourdock.