Defense contractors Lockheed Martin, General Dynamics and Raytheon spent a combined $33.4 million on lobbying in Washington last year, a 10 percent increase from 2010, as Congress and the Obama administration weighed cuts in the Pentagon budget.

A review of lobbying disclosures filed with the Senate by a Jan. 20 deadline showed that Bethesda-based Lockheed Martin, the world’s largest defense company, led such spending last year with $15 million for lobbying, a 19 percent increase.

Pentagon contractors face an era of limited government spending after an impasse on how to cut the federal budget left open the prospect of $1 trillion in defense cuts over a decade. Even with future cuts looming, defense companies focused their lobbying last year on protecting contracts and programs from immediate cuts, according to Michael Herson, president of American Defense International, a defense lobbying and business-development firm in Washington.

“The contractors were focused on their programs in fiscal year 2012 — that was the more certain problem at hand,’’ Herson said in an interview.

General Dynamics, of Falls Church, the maker of Abrams tanks and Gulfstream business jets, spent $11.3 million on lobbying last year, a 4.6 percent increase. Raytheon, of Waltham, Mass., the world’s largest missile maker, spent $7.1 million, a 2.9 percent increase.

Northrop Grumman of Falls Church, the maker of the Global Hawk drone, spent $12.8 million in 2011, a 19 percent decrease, after it spun off its shipbuilding unit. That operation, now Huntington Ingalls Industries of Newport News, Va., reported $4.4 million in lobbying expenses.

Congressional cuts

Congress approved in December $518 billion for core defense programs in fiscal 2012, a $21 billion reduction from the Pentagon’s request. For operations in Afghanistan and Iraq, Congress approved about $115 billion.

A congressional supercommittee assigned to reduce the deficit by at least $1.2 trillion failed to reach an agreement in November. That triggered automatic defense cuts of $500 billion, excluding interest savings, as stipulated under the budget control act President Obama signed into law in August.

The automatic cuts, also known as a sequester, slated to start taking effect in January 2013, would be in addition to about $490 billion that the administration already plans to cut through 2021.

“A possible sequester was out of our control and was uncertain’’ so it wasn’t the focus of defense-contractor lobbying, according to Herson of American Defense International.

Instead, companies relied on lawmakers such as House Armed Services Committee Chairman Howard P. “Buck’’ McKeon (R-Calif.), and the Aerospace Industries Association to make the case against deep cuts, Herson said. Arlington-based AIA is a trade group that represents companies including Northrop, Lockheed Martin and Boeing.

AIA, which expanded its “Second-to-None’’ campaign promoting robust defense spending, was on course to almost double its lobbying spending for 2011.

For the first three reporting quarters of the year, the group spent almost $1.3 million, up from about $850,000 for all of 2010, according to the Senate’s lobbying disclosure database. Its lobbying expenses for the final quarter weren’t posted in the database as of Jan. 23.

“We have taken an active role in providing information and educating lawmakers and other policy makers on the impact that budget sequestration and other budget cuts will have on the economy, on jobs and on America’s industrial capability,’’ Cord Sterling, the trade group’s vice president for legislative affairs, said in an interview.

Northrop Grumman supports the group’s efforts to show “the contributions that the industry makes to the country,’’ Randy Belote, a company spokesman, said in an interview.

Lockheed’s F-35

While Lockheed Martin’s defense portfolio spans missiles to cybersecurity and shipbuilding, its top program is the F-35 Joint Strike Fighter, which Congress last year scrutinized over delays and cost overruns.

The F-35 is the Pentagon’s largest weapons program at $382 billion, with plans to buy 2,443 jets for the Air Force, Navy and Marine Corps.

For fiscal 2012, Congress reduced funding for both the Air Force and Navy versions of the F-35 jet. Lawmakers cut one F-35 plane from the Air Force’s request to buy 19 jets in the year and also reduced funding to buy advanced parts for both the Air Force and Navy versions of the aircraft.

Lockheed “has a strong interest in national security, homeland security and other issues including education and technology,’’ Jennifer Whitlow, the company’s vice president for media relations, said in an e-mailed statement.

Congress added $255 million to the Army’s $181.3 million request for upgrades of the Abrams tank built by General Dynamics. The funding was supported by Republican House Speaker John A. Boehner of Ohio, where the tank is assembled.

General Dynamics’ other top defense programs include the Navy’s DDG-51 destroyer and the Virginia-class submarine, the Joint Tactical Radio System, and the Stryker combat vehicles.

A spokesman for General Dynamics didn’t respond to e-mail requests for comment on the company’s lobbying spending.

— Bloomberg Government

Tony Capaccio in Washington contributed to this report.