CNN’s new “facts first” slogan fell flat Tuesday when reporter Jeremy Diamond attempted to fact-check President Donald Trump’s claim that Sen. Bob Corker (R-TN) helped ease the passage of the Iran deal.

Trump’s exact words on Twitter were that Corker “helped President O give us the bad Iran Deal.” Diamond, mis-quoting Trump, replied that the president’s claim that Corker “supported the Iran deal” was “just not true.”

In fact, it is CNN that is lying.

In 2015, as President Barack Obama prepared to force through the Iran deal, it became clear that the administration had no intention of submitting the agreement to Congress for approval. The U.S. Constitution’s Treaty Clause says that two-thirds of the Senate must approve any treaty. The Iran deal — one of the biggest and most important deals negotiated by any administration — was certainly no “executive agreement.” It needed to be ratified — or rejected.

But rather than stand up for the Senate and the Constitution, Sen. Corker and Sens. Bob Menendez (D-NJ) and Lindsey Graham (R-SC) devised a half-measure called the Iran Nuclear Agreement Review Act, which would give Congress the power to disapprove of the Iran deal by passing a resolution in both houses. Many opponents of the Iran deal hailed the new legislation, and Obama threatened to veto it. But suddenly, Obama dropped that threat.

One reason Obama backed away was that it was clear that the “Corker bill,” as it was known, was going to pass with a veto-proof majority. But another reason was that the Corker bill made it easier, not harder, for the president to pass the Iran deal through Congress. Few people outside of Breitbart News noticed the Corker bill’s fatal flaw: if Obama vetoed a resolution of disapproval, he would just need one-third of either house to defeat an override effort.

As Breitbart News noted in April 2015: “[T]he text of the bill now before Congress would actually make an Iran deal easier to approve — and would do so by gutting the Senate’s constitutional power over treaties.” Only one Senator, Tom Cotton (R-AR), opposed the Corker bill and its the deceptive mathematics. And its futility was proven when Democrats in the Senate filibustered to prevent the Iran deal from even coming up for a vote on the floor.

Thus did Corker make it easier for Obama to force through the Iran deal. One could argue that Corker subjectively wanted to stop the deal. But Trump’s tweet is not “false,” as alleged by CNN’s Diamond in a dishonest “Facts First” segment that misquoted Trump and failed to mention the Constitution.

Worse, Diamond actually said on the air: “This bill was the bill that gave Congress the ability to actually weigh in on the Iran deal, which otherwise the Obama administration would have gone unilaterally and passed this motion by itself.” It was the Constitution that gave Congress that power, and the Iran deal was indeed unilateral — it was never “passed” by anyone.

Had Corker done his job, he would be on steadier ground in his fight with Trump. And the world would have been safer today.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named one of the “most influential” people in news media in 2016. He is the co-author of How Trump Won: The Inside Story of a Revolution, is available from Regnery. Follow him on Twitter at @joelpollak.