Many domestic manufacturers are pushing for freer trade despite the mounting difficulties some are having with the rising volume of imports, the Wall Street Journal reported today. The manufacturing sector is one of trucking's largest and most important customers. The Manufacturers Alliance, a research group whose members include many large companies such as Caterpillar Inc., had endorsed a multilateral free-trade agreement for the world's manufacturers that would essentially strip away tariffs and combine regional and bilateral trade pacts under one umbrella.However, many smaller manufacturers have complained about unfair competition and are starting to apply pressure on the government to restrict imports, whether made by foreign firms or U.S. firms that have located abroad, the Journal said. Trade is expected to be a topic discussed at World Trade Organization talks starting next month in Mexico.