President Donald Trump’s trade war has sparked a surge in lobbying in the fight over his tariffs.

American companies and business groups mostly opposing Trump’s tariffs closed out an active year of lobbying on trade issues in 2018. They expect a busy 2019 as the trade conflict continues and action is pending in Congress on a renegotiated deal with Mexico and Canada.

Trump’s duties on imports of steel, aluminum and Chinese goods—as well as his threat to impose tariffs on automobiles—plus the updated North American Free Trade Agreement were key targets of lobbying in the final three months of 2018, according to disclosure reports filed with Congress by Tuesday’s deadline.

There were at least 341 reports for the fourth quarter that included “tariff” as a specific lobbying issue, more than twice the number filed during the same period in 2017, according to posted filings. Lobbying records show aggregated spending on lobbying, rather than breaking it down by individual issues.

Hundreds of reports also listed Nafta, the metals tariffs meant to bolster U.S. producers, and the duties on Chinese imports that Trump imposed in response to a trade imbalance and allegations of unfair trade practices.

“While the White House is correct to focus on China’s unfair trade practices, tariffs are a blunt instrument that harms American consumers and our economy,” Michael Petricone, senior vice president of government and regulatory affairs for the Consumer Technology Association, said in a statement. Tariffs are costing the technology industry $1 billion a month, he said.

Trump ratcheted up the conflict in late September by imposing tariffs on an additional $200 billion worth of Chinese goods—after hitting $50 billion in products earlier in the year—and has threatened duties on $267 billion more. China responded with duties of its own on U.S. exports.

While Trump and Chinese President Xi Jinping agreed on Dec. 1 to temporarily freeze tariffs to allow for negotiations—delaying until March 1 a scheduled Jan. 1 increase in U.S. duties on the $200 billion in goods—companies continued to push for exclusions from earlier levies. They also sought relief from separate duties imposed on nearly all countries’ imports of steel and aluminum and opposed tariffs on automobiles that Trump keeps threatening.

The National Retail Federation reported spending $2.5 million on lobbying in the fourth quarter, up from $1.9 million during the previous three months. Much of the increase was attributable to the group’s efforts on trade and tariffs, said David French, senior vice president of government relations.

“We increased the tempo of some of our tariff-related lobbying,” he said.

U.S., Canadian and Mexican leaders signed a renegotiated Nafta on Nov. 30, and now the push is on to get Congress to ratify it. American companies and trade groups wanted to ensure that all three countries are part of any pact—rather than dealing with the countries separately—and that the existing deal not be terminated before a new one is approved.

Frank Samolis, partner and co-chairman of the International Trade Group at Squire Patton Boggs, said there’s also been activity on other trade issues, including Brexit and U.S. negotiations this year on trade deals with the European Union, Japan and the U.K.

Samolis said that “2019 will be an even busier year.”

Reports show the targets of the trade lobbying included the administration and Congress, though lobbyists have said the usual approaches have proven less effective with Trump as president. They’re resorting to creative tactics such as running ads on “Fox and Friends,” which Trump is known to watch.

Besides direct lobbying of the executive branch and Congress, businesses and trade groups have been trying to get information into the public domain to influence public opinion about the negative effects of tariffs, said trade lawyer David Cohen of Sandler, Travis & Rosenberg, PA.

“Lobbying efforts throughout the year have mostly walked a thin line of trying to support the legitimate wrongs that have served as the underpinnings and justification of the tariffs while objecting vehemently to the means the president is using to accomplish his goal,” Cohen said.

The U.S. Chamber of Commerce’s lobbying efforts in the fourth quarter included laying the foundation for congressional approval of the new Nafta pact and urging the administration to remove steel and aluminum tariffs on Canada and Mexico, spokeswoman Blair Latoff Holmes said in a statement.

The American Chemistry Council and other trade groups said in their reports they lobbied on legislation that would require the president to obtain congressional approval before imposing tariffs on national security grounds, as Trump did on metals imports, and as he’s considering doing on cars and auto parts.

Legislation to limit Trump’s ability to levy duties unilaterally did not advance last year. Republican Senator Chuck Grassley of Iowa, now the Finance Committee chairman, has said he intends to review the president’s use of his authority. Bloomberg has reported that Trump is expected to urge Congress, in his State of the Union address, to expand his powers on trade.