WASHINGTON (AP) — President Barack Obama sought to clamp down Monday on power plant emissions with a federal plan that — if successful — would attempt to slow global warming by dramatically shifting the way Americans get and use electricity.

Touting the plan at a White House ceremony, Obama described his unprecedented carbon dioxide limits as the biggest step ever taken by the U.S. on climate change. On that point, at least, his opponents agreed. They denounced his proposal as egregious federal overreach that would send power prices surging, and vowed lawsuits and legislation to try to stop it.

"We're the first generation to feel the impact of climate change, and we're the last generation that can do something about it," Obama said. He added, "We only get one planet. There's no Plan B."

Obama's announcement sets off a years-long process for states to figure out how to comply. By the time it takes effect, Obama will be long out of office.

Still, Obama was hoping that the plan would bolster his status as the first president to seriously tackle climate change, and galvanize other countries to take aggressive action to achieve a global climate treaty this year.

Under the plan, first proposed last year, the U.S. must cut power plant emissions 32 percent by 2030, compared to 2005 levels. The Obama administration said it would cost $8.4 billion annually by 2030, but argued that power bills would decrease because people would use less electricity and rely more heavily on low-cost sources like wind and solar. The energy industry has dismissed those estimates as overly rosy.

Here's what lies ahead for Obama's controversial plan:

LAWSUITS ABOUND

Within minutes of Obama unveiling his plan, numerous groups said they'll sue.

The Murray Energy Corp., a coal mining company, planned to file five lawsuits. In the coal-heavy state of West Virginia, state Attorney General Patrick Morrisey said his state was "launching an aggressive legal campaign" — and predicted that 20 to 25 states would join.

"Their legal foundation is very, very shaky," Morrisey said of the Obama administration.

Morrisey echoed other critics in arguing Obama has exceeded his authority by requiring statewide steps like renewable energy use and reduced energy demand. He said under the Clean Air Act, the government can only require steps within a power plant.

In another hint of the likely legal strategy, Morrisey cited the Constitution's 10th Amendment, which protects the states against undue intrusion by Washington.

PASSING THE BATON

Another key threat could come from Obama's successor. Because of the lengthy timeline — states have 7 years to start complying — the next president will have ample time to unravel the rules if he or she chooses to do so. That means that a cornerstone of Obama's presidential legacy rests in someone else's hands.

Hillary Rodham Clinton, the front-runner for the Democratic nomination, has pledged to defend the rule if elected. But the Republican field is making the opposite pledge.

GOP candidates claimed Obama's actions are burdensome to business and block job creation. Wisconsin Gov. Scott Walker said the regulation was like a "buzz saw" to the U.S. economy, while former Florida Gov. Jeb Bush said the plan "will throw countless people out of work and increases everyone's energy prices."

STATE OF AFFAIRS

Each state now has an individualized emissions reduction target to meet — in some cases higher than Obama's previous proposal, in some cases lower. States must submit implementation plans by 2018.

Starting in 2022, states will have to reduce emissions, but the cuts are phased in gradually until 2030, when states must meet their overall target. In 2020 and 2021, states that invest in renewable sources like wind and solar will earn credits that they can store away to offset pollution emitted later.

To meet their targets, states can use a variety of measures, including new technology to capture emissions, regional cap-and-trade schemes and energy efficiency programs.

Senate Majority Leader Mitch McConnell, R-Ky., has urged GOP governors not to comply, and many have agreed. McConnell also vowed Monday to use legislation to stop the plan, although Obama's veto power makes that option unlikely.

If a state refuses to submit a plan, the Environmental Protection Agency can impose one. EPA Administrator Gina McCarthy said the administration will immediately issue a model federal rule that states can use.

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Reach Josh Lederman at http://twitter.com/joshledermanAP