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First the bomb, now climate change.

For the second time in a month, the Senate's Republican leadership is warning potential partners in an international agreement that the United States may balk at any deal.

On Tuesday, the Obama administration submitted its plan for cutting US carbon emissions as part of UN negotiations aimed at reining in global warming. That drew a swift response from Senate Majority Leader Mitch McConnell, who warned other countries that Washington might not follow through.

The senator from the coal producing state of Kentucky said the Obama administration's current plans to reduce carbon emissions are already being challenged in court.

"Even if the job-killing and likely illegal Clean Power Plan were fully implemented, the United States could not meet the targets laid out in this proposed new plan," McConnell said in a written statement. "Considering that two-thirds of the US federal government hasn't even signed off on the Clean Power Plan and 13 states have already pledged to fight it, our international partners should proceed with caution before entering into a binding, unattainable deal."

McConnell was also among the 47 GOP senators who signed an open letter to the clerical leaders of Iran in March, warning that any deal the Obama administration reached in nuclear talks with the Islamic republic could be null and void under a new president.

And Senator James Inhofe, recently seen throwing a snowball on the Senate floor to prove climate change isn't happening, said the administration's pledge "will not see the light of day with the 114th Congress."

"When a treaty comes before the Senate, I fully expect for a majority of my colleagues to stand with the rest of Americans who want affordable energy and more economic opportunity, neither of which will be obtainable with the president's current climate deal," Inhofe said in a written statement. Inhofe, from the oil- and gas-rich state of Oklahoma, chairs the Senate's Environment and Public Works Committee.

The White House release of the US emissions pledge, known as an Intended Nationally Determined Contribution (INDC), followed up on a commitment President Obama first made in a US-China agreement in November. The US carbon cutting plan calls for a reduction in greenhouse gas emissions by 26-28 percent below 2005 levels by 2025. It would double the pace of carbon cuts after 2020 and reduce overall emissions by more than 80 percent by 2050.

The goal of the UN climate talks is to reduce global emissions enough to keep the world from warming by an average of more than 2 degrees Celsius (3.6 Fahrenheit) over pre-industrial times by 2100. Negotiators are hoping to have a pact ready to sign at a December conference in Paris.