By Alex Leary

President Trump ordered a payment program be established to help lobster producers amid ongoing trade tensions, boosting an industry that is iconic in Maine, a state the president has targeted in his re-election campaign.

Under a memorandum Mr. Trump signed Wednesday, Agriculture Secretary Sonny Perdue would set up a program to "provide assistance to fishermen and producers in the United States lobster industry that continue to be harmed by China's retaliatory tariffs."

China put tariffs on U.S. lobster imports as Mr. Trump ramped up his own levies on Chinese-made goods but separately under the phase one trade deal, China agreed to make some lobster purchases. The memorandum calls for tracking progress of those commitments and, if they aren't met, imposing retaliatory tariffs on Chinese seafood.

In the phase-one deal signed in February, China agreed to purchase $32 billion worth of additional U.S. agricultural products, including seafood. It didn't specify the target purchasing amounts for that category. White House trade adviser Peter Navarro said China agreed to some exclusions of its lobster tariffs equal to $150 million. The payment program would be on top of that.

"The assistance program is designed to make whole America's lobster fishermen for the harm they have suffered at the hands of the Chinese Communist Party's unfair retaliatory tariffs," Mr. Navarro said.

"The action will also help ensure China fulfills its purchase commitments under the Phase One deal even as it seeks to address the harm our lobster fishermen are now experiencing from the ripple effects of the Canada European Union Trade Agreement -- U.S. exports to the EU are down dramatically and Canadian exports are soaring."

The move comes as Mr. Trump has looked at Maine to his re-election hopes, including making a visit there earlier this month. The state has only four electoral votes, but Mr. Trump has been looking to expand states he won in 2016 and his campaign has had a rough few months. A string of recent polls show him trailing presumptive Democratic nominee Joe Biden.

During the trip, Mr. Trump said he was reopening fishing in the Northeast Canyons and Seamounts Marine National Monument off the coast of New England to commercial fishing, which had been put off limits under the Obama administration. The lobster issue came up during that visit.

Republican Sen. Susan Collins of Maine, who has sometimes been critical of the president, is facing a tough re-election bid.

Maine splits its electoral votes based on results in congressional districts, and in 2016, three went to Hillary Clinton and one to Mr. Trump. Hanging onto that one vote -- or picking up more -- could be crucial in a close election.

Sen. Angus King (I., Maine) praised the administration for the move.

"China was our fastest-growing market and it just went to zero," he said in reference to trade tensions with China. Mr. King along with Ms. Collins and Democratic Reps. Chellie Pingree and Jared Golden asked the administration a year ago to include lobstermen in its aid packages to farmers. "This should be very, very helpful to our industry."

Asked about the political implications of such a move in an election year, Mr. King chuckled and said he won't "bite the hand that feeds you" and said that he supports the administration's action.

--Natalie Andrews contributed to this article.

Write to Alex Leary at alex.leary@wsj.com