NEW YORK (AP) — Steps that President Barack Obama has taken to help the environment must be protected, former Secretary of State Hillary Rodham Clinton said, but she avoided the contentious issue of the Keystone XL pipeline in remarks to a group that vigorously opposes it.

Clinton spoke Monday at a dinner of the League of Conservation Voters, which has come out strongly in urging elected officials to reject the project. Her speech followed a private fundraising event for a senator who supports the pipeline.

Clinton stopped short of making any direct reference to the Keystone project, which would run from Canada to Nebraska, connecting existing pipelines to carry more than 800,000 barrels of crude oil a day to refineries along the Texas Gulf Coast.

She told the audience that this is an exciting time for environmental action, and mentioned progress like the agreement the U.S. reached with China a few weeks ago over cutting emissions, which Clinton said must be safeguarded.

The steps "that President Obama has taken must be protected at all costs," Clinton said.

She also acknowledged challenges.

"There is no getting around the fact that the kind of ambitious response required to effectively combat climate change is going to be a tough sell at home and around the world," she said. "Our economy still runs primarily on fossil fuels and trying to change that will take strong leadership."

Before Clinton attended the dinner, she was at a fundraiser for Democratic Sen. Mary Landrieu of Louisiana, who supports the Keystone project. Landrieu faces Republican Rep. Bill Cassidy in Saturday's runoff Senate election.

Landrieu, who trails Cassidy in public polls, has been a vocal supporter of her home state's oil and gas industry and unsuccessfully sought Senate approval of the Keystone XL pipeline.

Earlier this year, Clinton told audiences in Canada that it would not be appropriate for her to comment on the pipeline, given her previous role as secretary of state in Obama's administration.

The State Department has overseen a long-stalled review of the project. While environmentalists have opposed the plan, labor unions have backed it because of the potential economic benefits.

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Associated Press writer Ken Thomas in Washington contributed to this report.