MILAN — Leading U.S. Democrat Nancy Pelosi on Monday called the pope's climate encyclical "an important new effective asset" in pushing forward policy to slow global warming by bringing aboard a new audience.

Pelosi said the pope's manifesto, which called for a bold cultural revolution, carried a moral authority with the power to directly shape public sentiment on the issue, and perhaps in turn influence members of Congress.

The California Democrat and House minority leader made the comments as President Barack Obama prepared to unveil later in the day new regulations demanding steep greenhouse gas cuts from U.S. power plants.

"Someone who might reject a policy initiative spoken by a government official in the United States really cannot ignore his holiness Pope Francis on this subject," Pelosi said during a visit to the Milan Expo 2015 world's fair on food security issues.

"We see that as an important, new effective asset," she said.

She said the issue of climate change was growing more urgent.

"We don't want the Congress of the United States to be the last to realize our responsibility, once again, to our children and the future," she said.

Pelosi is leading a high-level congressional delegation on a trip to Italy and Ukraine.

After meeting leading lawmakers in Rome on Sunday, the delegation visited Expo with stops at the Italian and U.S. pavilions. More than 2 million people visited the U.S. pavilion during the first three months of the world's fair, which is expected to attract 20 million visitors.

Pelosi noted that there is a direct connection between climate change and the issues being tackled at the six-month world's fair that ends Oct. 31, including sustainable agriculture and nutrition.

"Everything in nature is connected. The encyclical said that very well," she said.