WASHINGTON (Reuters) - Chief executive officers of 16 companies, including Boeing Co BA.N, Caterpillar Inc CAT.N and General Electric Co GE.N, have urged the U.S. Congress to pass a comprehensive tax code rewrite, including a controversial border tax.

FILE PHOTO -- Cargo containers sit idle at the Port of Los Angeles as a back-log of over 30 container ships sit anchored outside the Port in Los Angeles, California, February 18, 2015. REUTERS/Bob Riha, Jr./File Photo

In a letter to Republican and Democratic leadership on Tuesday, the CEOs said a Republican-proposed border adjustment tax would make U.S.-manufactured products more competitive abroad and at home by making imported goods face the same level of taxation.

It was the latest move in a back-and-forth lobbying effort from companies over changes to the tax code.

Republican House Speaker Paul Ryan has proposed lowering the corporate income tax to 20 percent from 35 percent, imposing a 20 percent tax on imports and excluding export revenue from taxable income.

The proposal has drawn opposition from large U.S. corporations that require imports, like retailers and auto manufacturers. Those that export much of their output tend to support the tax code changes.

In a separate report, the technology policy group Information Technology & Innovation Foundation called on Congress to lower the corporate rate, but warned that elements like the border tax risked jeopardizing the effort.

“In order for corporate tax reform to succeed in boosting economic growth, lawmakers should focus on the most essential changes that will have the greatest effect on innovation and competitiveness,” Joe Kennedy, an ITIF senior fellow, said in a statement.

The ITIF is a nonpartisan think tank whose board members include representatives from large technology companies such as Apple Inc AAPL.O, International Business Machines Corp IBM.N and Intel Corp INTC.O.

Tony Simmons, CEO of McIlhenny Co, which produces Tabasco, said while his company imports peppers to make its hot sauce, it still expects a net gain.

“We export about 40 percent of our total sales – so the border adjustment works both ways for us,” Simmons said on a call Tuesday with reporters. “Our federal rate would drop.”

A group of retail CEOs met last week with President Donald Trump and congressional leaders to argue against the border adjustment tax.

Trump is expected to release his tax proposal in the coming weeks. While he has said the border adjustment tax is too “complicated,” his administration has said taxing goods from Mexico could fund construction of a wall along the border.

The letter supporting the border tax was signed by CEOs from Boeing, CoorsTek, Caterpillar, Dow Chemical Co DOW.N, Celanese Corp CE.N; GE, Celgene Corp CELG.O, Eli Lilly and Co LLY.N, Raytheon Co RTN.N, Merck & Co Inc MRK.N, S&P Global Inc SPGI.N, Oracle Corp ORCL.N, United Technologies Corp UTX.N, Pfizer Inc PFE.N and Varian Medical Systems Inc VAR.N.