The Obama administration's proposed greenhouse gas emissions rule for existing power plants is "changing the tone" of the international dialogue on climate change, Environmental Protection Agency Administrator Gina McCarthy said Monday.

McCarthy said other big polluters like China and India have taken note of the United States' push to tamp down power-sector emissions. She said the U.S. effort has helped grease dialogue heading into international negotiations next year in Paris, where countries will look to score enough carbon-cutting commitments by 2020 to avoid a 2 degree Celsius temperature rise by 2100.

"This is a global problem that needs a global solution. But more importantly, for our rule in particular we know that if the U.S. isn't in a leadership position … then a global solution won't make it to the table," McCarthy said during a media call previewing four public hearings the EPA is holding in Atlanta, Denver, Washington and Pittsburgh to collect public comment on the power plant proposal.

The EPA's proposed rule aims to slash power-sector emissions 30 percent below 2005 levels by 2030, amounting to the most significant action the U.S. has taken on climate. President Obama has touted the proposed rule as a chance to lead on climate ahead of the Paris talks, hoping to secure buy-in from China, India and other polluters that have typically resisted such pacts.

The White House said last week that Obama plans to attend a U.N. climate summit this September in New York, which is serving as a prelude to the conference, a move that would underscore the emphasis he's placing on the negotiations.

Conservatives and industry groups say the EPA effort won't be enough to attract other big polluters. They contend the White House is putting too much stock in the goodwill of others, and have pointed to countries like Australia, which earlier this month repealed its carbon tax, as potential holdouts that would thwart a climate commitment. In the end, they say, the carbon regulations would leave the U.S. at an economic disadvantage.

McCarthy hit back against criticisms that the power plant rule would damage the economy — the EPA has cited potential benefits from improving power plant efficiency, bolstering the renewable energy industry and reducing medical costs from taking dirtier, older coal-fired power plants offline.

She said that "tensions are going down" at the state level after the initial rollout for the rule, which is scheduled for finalization next June. She said some states misunderstood what the EPA proposed rule calls for and noted that states can approach their carbon-reduction targets in whatever way they choose.

McCarthy said the EPA has learned it needed to smooth out some details with states just based from the first two months of comments, which is one of the reasons it is holding the public hearings this week. McCarthy didn't dismiss the prospect of potentially extending the 120-day public comment period, which some have called for given the proposed rule's significance and complexity.

"I don't want to comment on what we would do, but I think at this point we are providing tremendous opportunity for public comment," she said.