The U.S. Chamber of Commerce continued to dominate its peers on K Street by spending a whopping $100 million on lobbying and issue advocacy ads in 2010.

The business group spent less last year than in 2009, when it reported $123 million. A big chunk of the 2009 number went toward ads attacking the health care overhaul, said Bruce Josten, a lobbyist for the chamber. “We had seven months of health care ads in ’09 and two months of it at the start in 2010,” he added.

Tax issues were huge for the big-business association at the end of 2010. The chamber spent $36.4 million in the fourth quarter, according to just-filed Lobbying Disclosure Act reports. The chamber also lobbied on an increase to Small Business Administration loan limits, Wall Street reform, trade agreements with South Korea and Colombia, food safety legislation, and the health care overhaul.

Other big spenders included defense giants such as Boeing Co., which shelled out $17.9 million in lobbying in 2010, an increase of $1.1 million from the previous year. The Chicago-based aerospace contractor is in a pitched battle to win a lucrative Pentagon contract to manufacture a new generation of aerial tankers. Northrop Grumman Corp., a large defense company that dropped out of the bidding war for the tanker in 2010, spent $15.7 million on lobbying last year, up from $15.2 million in 2009.

The National Cable & Telecommunications Association also fattened its lobbying tab last year, spending $17.8 million compared with $15.9 million in 2009. The association was involved in a number of hot-button communications issues before the Federal Communications Commission, such as net neutrality rules.

General Motors Co., which emerged from bankruptcy last year, stepped up its federal lobbying. It spent $9.9 million in 2010, an increase of $1.3 million from the previous year.

Not all companies and associations reported increases in spending in 2010. The Business Roundtable, which experienced turnover in top leadership, disclosed spending $8.8 million last year, a decrease from the $13.4 million it spent in 2009.