NEW YORK (AP) — Former Secretary of State Hillary Rodham Clinton said steps President Barack Obama has taken to help the environment must be protected at all costs.

Clinton spoke Monday at a dinner of the League of Conservation Voters in New York as she weighs another presidential campaign.

She told the audience that this is an exciting time for environmental issues, and mentioned steps like the agreement the U.S. reached with China a few weeks ago over cutting emissions.

"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."

Clinton didn't make any reference to the high-profile Keystone XL pipeline, which is proposed to run from Canada to Nebraska, where it would connect with existing pipelines to carry more than 800,000 barrels of crude oil a day to refineries along the Texas Gulf Coast. It has been vigorously opposed by environmental groups.

Before Clinton attended the dinner, she was at a fundraiser for Democratic Sen. Mary Landrieu, who supports the pipeline. 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.

Clinton has declined to take a position on the pipeline, telling audiences in Canada earlier this year that it would not be appropriate for her to comment on it, given her previous role in Obama's administration.

___

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