"It was a decision of global importance, not made based on science and diplomacy, but one which appears to have been determined by a political calculus
," Smerconish said of Trump's announcement this week to pull out of the environmental agreement adopted by 195 nations in 2015.
"This decision was the delivery of a campaign pledge made to the 46% of voters who carried him to victory, especially in Rust Belt states like Pennsylvania, Michigan, Ohio and Wisconsin."
Trump's voters had "little show for their support" so far, Smerconish insisted.
"The President has been unsuccessful implementing the travel ban
. There's been no repeal and replacement of Obamacare
. No tax reform
. He hasn't ended NAFTA. China has not been labeled a currency manipulator
. No shovels put in the ground for the border wall
. Not even the moving of the embassy in Israel," he said, referring to Trump's decision to renew the waiver keeping the US Embassy in Tel Aviv
Trump needed to deliver on one of his campaign promises, Smerconish said, "so he cloaked his opposition in the promise of jobs, casting our lot with fossil fuels and not with renewable energy -- all to throw his base a bone."
By joining Nicaragua and Syria as the sole holdouts on the Paris Agreement, the United States has "abdicated our leadership role and provided China with a perfect rebranding opportunity," the CNN host said.
Now, he argued, it's an open question about what America's role in the world will be.
"Do Americans care what their role will be? Are we back to the isolationist days of the 1930s and '40s when FDR ran on the platform of keeping us out of war?" he asked.