By Christi Parsons,

Julie Makinen and Michael A. Memoli

Tribune Washington Bureau (MCT)

BEIJING _ A landmark agreement on climate change between the U.S. and China, the world’s top two polluting nations, faced immediate challenges from experts who warned that it would require an overhaul of China’s economy and from Republicans in Congress who vowed to undermine the deal.

President Barack Obama’s ramped- up push on environmental issues set up a clash with GOP leaders, who blasted the far-reaching agreement with China as bad for business and promised to try to block the regulations necessary to meet its targets for curbing carbon emissions. Administration officials asserted that they would not be deterred.

The standoff was the clearest sign yet that Obama plans to prioritize his agenda _ and his legacy _ over hope of sowing goodwill with the incoming Republican- controlled Congress. Even as both parties promised to heed voters’ calls to find common ground after last week’s midterm election, the White House and Republican leaders have since drawn lines in the sand over immigration as well as environmental policy.

The China pact signaled that the president “has no intention of moving towards the middle,” Senate Republican Leader Mitch McConnell of Kentucky told reporters Wednesday.

Sen. James Inhofe of Oklahoma, likely to succeed Sen. Barbara Boxer, D-Calif., as chair of the Environment and Public Works Committee in the Republican-led Senate next year, called the deal a “nonbinding charade.”

“I will do everything in my power to rein in and shed light on the EPA’s unchecked regulations,” he said. Inhofe, perhaps Congress’ most prominent climate change skeptic, has long criticized the Environmental Protection Agency.

Administration officials touting the deal appeared unfazed by Republican promises to throw up roadblocks, describing congressional support as a bonus but not a necessity.

“It would be nice if we had some help and support from the Congress,” said a senior administration official, who requested anonymity in discussing strategy. “But we think we have the ability under laws that have already been passed by Congress _ principally the Clean Air Act, but other laws as well _ to get these reductions … with authorities we already have.”

At the heart of the deal announced Wednesday, during Obama’s visit to Beijing, are nonbinding goals for alternative energy use and lower greenhouse gas emissions. Obama said he had agreed, for example, that the U.S. would cut net emissions at least 26 percent by 2025. Experts note that the unexpectedly high targets can be reached only if both countries enact new policies that speed up the transition from carbon-based fuels.

“It’s an ambitious target without having Congress weigh in, but it is doable using existing authority,” said Alden Meyer of the Union of Concerned Scientists. “But the administration will have to look across industrial sectors and under every rock and pebble they can find” for the cuts needed.

In agreeing for the first time to cap carbon emissions, Chinese President Xi

Jinping broke from his nation’s policy of instead trying to slow the pace of increase. It’s unclear how difficult it will be for

Beijing to make good on its new goals, which include setting a target for 20 percent of its energy consumption to come from alternative fuels by 2030 and capping emissions by then. The agreement does not set a target level of pollution for 2030 and does not specify whether China would lower emissions after that date or simply level them off.

Still, most experts said the new goals would require substantial changes to China’s coal-addicted economy.

“China will need to adjust its economic structure, limit its use of coal and scale up non-fossil energy supply,” said Ranping Song, who leads the World Resources Institute’s China Climate and Energy Program.

The government has been considering policy options, such as capping coal use and putting a price on carbon, Song noted. “But robust, on-the-ground implementation of those policies requires strong political will.”

Such resolve is building fast in China, spurred by the country’s debilitating and embarrassing smog problem, said Bonnie Glaser, a China expert at the Center for Strategic and International Studies.

“Pollution itself has become, I think, a threat to the legitimacy of the party and the political stability in China,” Glaser said. “And the failure to take action on this issue is really going to come back and bite the Communist Party. I think Xi Jinping has realized this.”The deal, she noted, is not as politically controversial in China as it is in the U.S.”Given the reaction from Republicans today, it’s the president that has the uphill battle much more than Xi Jinping does,” Glaser said.

Obama pegged his climate change policy to a handful of executive actions and a slew of carbon-reducing regulations already in the pipeline.

A White House official said the administration believed the new goals could be met through current regulations _ including new standards for coal-fired power plants, heavy-duty-vehicle fuel economy standards and promised methane emissions rules _ as well as unnamed “new and expanded” policies.

Republicans, and some Democrats, already have found a way to test Obama’s climate policies. Both the House and Senate are set to soon consider measures that would advance the long-delayed Keystone XL pipeline project. In the Senate, the legislation would be put forward by Sen. Mary L. Landrieu, a Democrat in a re- election runoff in Louisiana, where the project has solid support.

The president has said he will approve the project only if it can be proved not to worsen emissions of greenhouse gases that lead to global warming.

Landrieu’s call for a vote could force the administration to end its delay and take a position on the project. The White House did not have an immediate comment on the potential vote.

McConnell has indicated that he’s ready to test Obama’s commitment to the ambitious deal with China.

Republicans are considering attaching legislation aimed at the regulations, such as measures undermining the EPA’s authority or slowing the rule-making process, to spending proposals. The so-called policy riders would force the president to either approve the limits on his authority or veto the budget bills and risk a major showdown with lawmakers.