Hundreds of Democrats from 32 states are aligning against the centerpiece of President Obama's climate change agenda, the Clean Power Plan, which they say will cause unnecessary economic harm from increased reliance on renewable energy.

"As Democrats committed to a prosperous America and a healthy environment, we believe the United States has a unique opportunity to lead the world in addressing the global climate challenge, and yet do so, as we must, without unduly burdening the American economy or the American people," the Democratic coalition called CoalBlue said in a letter sent Tuesday to Obama.

The group joined with hundreds of Democratic officeholders and state, local and party officials in telling Obama that the Environmental Protection Agency's emission rules for power plants pose "serious and overriding concerns," representing the wrong approach to the problem of climate change.

"If we are going to provide real leadership in the world community on climate, we cannot begin by implementing policies that have no hope of succeeding outside of the United States, or possibly even within the United States," said the group's chairman, former U.S. Rep. Zack Space of Ohio. His state is one of 27 suing the EPA over the Clean Power Plan.

Space's letter was sent after Republican attorneys general sent a seperate letter to the Secretary of State John Kerry and Obama, telling them to admit the illegality of the climate rules when attending a conference of world leaders next week on a global deal to lower emissions. The states argue that the rules are unconstitutional because EPA is overstepping its authority under the law.

CoalBlue's message is directed at the president ahead of the United Nations conference in Paris, which starts Nov. 30. Space says an agreement would pose problems for U.S. reliance on low-cost coal in favor of less reliable renewable energy. At the same time, big greenhouse gas emitters such as China and India are expected to continue their use of low-cost fossil fuels to propel their economies.

"The EPA, while well intentioned, has lost sight of the importance of preserving affordable and reliable energy in its pursuit of clean energy," Space said. "As such, it has put forth policies that other nations, particularly in the developing world, are unlikely to follow, and that risk the loss of support at home."

The letter says "this imbalance is a serious failing that demands immediate attention. More than talk about 'policy parity,' we must make it real."

The letter was signed by 626 state and local officials from nearly three dozen states, including 177 state legislators, 278 local elected officials and 148 Democratic Party officials.

The group says "to be focused only on clean is not enough." Energy production must be affordable and reliable, which has driven environmental progress for decades. It says instead of the EPA regulations, a new energy technology revolution needs to be led by the U.S. to improve fossil energy use in the developing world, not to limit it.

The letter points out that the EPA emission rules do not promote new coal technologies, but instead effectively ban them by making them cost prohibitive.

"The American people will object, and other nations of the world will not follow, if the path we chart is one of more expensive, less reliable energy," the letter reads. "True leadership requires the pursuit of policies that will make all forms of clean energy less expensive, be they renewable or fossil-based, and as reliable as current baseload coal-fired generation."