WASHINGTON (AP) — President Barack Obama is looking to create the largest marine preserve in the world by protecting a massive stretch of the Pacific Ocean from drilling, fishing and other actions that could threaten wildlife, the White House said.

Aiming to protect marine wildlife, Obama will also direct the government to create a program to deter illegal fishing. The executive steps come as Obama is searching for ways to leave his second-term mark on the environment despite opposition from many Republicans in Congress.

Obama was to announce the steps Tuesday in a video message to those participating in an "Our Ocean" conference that the State Department and Secretary of State John Kerry are hosting.

Officials said Obama is considering a massive expansion to the Pacific Remote Islands Marine National Monument. The protected waters surround a group of mostly uninhabited islands, controlled by the U.S., that sit between Hawaii and American Samoa.

But the White House hasn't settled on the final boundaries for the preserve. The administration said it planned to solicit input from fishermen, scientists, politicians, experts in conservation and others before the new protections take effect.

The White House's Council on Environmental Quality said the waters in the south-central Pacific Ocean contain "some of the most pristine tropical marine environments in the world."

"These tropical coral reefs and associated marine ecosystems are also among the most vulnerable areas to the impacts of climate change and ocean acidification," the White House said in a statement.

Obama is also vowing to create a government program to combat black market fishing and seafood fraud, in which seafood products are mislabeled to hide their origin. The White House said 20 percent of the wild marine fish caught each year are part of the black market, at a cost of $23 billion to the legitimate fishing industry.

"President Obama's announcement is a historic step forward in the fight against seafood fraud and illegal fishing worldwide," said Beth Lowell of the conservation group Oceana. "This initiative is a practical solution to an ugly problem and will forever change the way we think about our seafood."

While drawing on authority that's within his power as president, the moves could rankle some GOP lawmakers who say Obama is exceeding his authority by going around Congress to promote his agenda on issues like the environment, immigration and gay rights. Earlier this month Obama unveiled sweeping new pollution limits on U.S. power plants amid signs that Congress wouldn't act soon to combat the heat-trapping gases blamed for global warming.

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