Many factors are to blame for the dying prospects of reviving the 2015 Iran nuclear deal. But perhaps nothing has hobbled the Biden administration’s efforts more than the legacy of President Donald Trump.

It was Trump, of course, who withdrew in 2018 from the nuclear pact brokered with Iran by the Obama administration, calling it "the worst deal ever.”

But Trump did more than pull the plug. U.S. officials and analysts say his actions vastly complicated America’s ability to negotiate with Iran, which has made demands outside the nuclear deal that President Joe Biden has refused to meet without receiving concessions.