Joe Scarborough said Thursday "a storm is gathering" for 2018 because of the Trump administration's "undermining of democratic values that poses an even greater threat to our Constitution and country."

"There is every reason to believe that 2018 will be the most consequential political year of our lives," Scarborough, co-host of "Morning Joe" on MSNBC, wrote in an op-ed in The Washington Post.

He detailed how President Donald Trump spent 2017 — a "horrid year" — undermining many of the principles that have guided the United States since its founding and eroding global relationships forged by war and diplomacy.

"World leaders continue to watch dumbstruck as the United States retreats from organizations that were created following the allies' victory over Hitler," Scarborough said.

"Those same alliances that Trump now undermines with reckless tweets and discarded treaties carried the United States to victory in the Cold War.

"But this is a White House that heaps contempt on history," he added. "And so, America's dangerous retreat from the world continues."

Scarborough then quotes from Winston Churchill's 1948 book — "The Gathering Storm" — on World War II: "'On the morrow of the Republican success isolationist conceptions prevailed.'"

"The British prime minister," Scarborough explained, "believed Hitler's rise proved, above all else, 'how absolute is the need of a broad path of international action pursued by many states in common across the years, irrespective of the ebb and flow of national politics.'

"But this president is ripping apart the carefully woven fabric of U.S. foreign policy that bound administrations together from Franklin D. Roosevelt to Ronald Reagan to Barack Obama, and across the American century."

Scarborough said "The Gathering Storm" was on his holiday reading list because Republican strategist Steve Schmidt insisted "Churchill’s ominous warnings to future generations will be more relevant to 2018 than at any time since it was written in the years after World War II."

Again, quoting the late prime minister: "'The malice of the wicked was reinforced by the weakness of the virtuous . . . They lived from hand to mouth and from day to day, and from one election to another . . . The cheers of weak, well-meaning assemblies soon cease to echo, and their votes soon cease to count. Doom marches on.'

"Schmidt is right," Scarborough concluded. "The storm is gathering.

"And how we respond in the months ahead may determine our fate for years to come."