Newsom explained that he spoke to the president "because I wanted to extend to him my appreciation" for his visit to California areas hit by wildfires and to "express the fact that the people in those communities were grateful to him". Twenty-five people on California's death row have exhausted all of their appeals.
Newsom also is withdrawing the lethal injection regulations that death penalty opponents already have tied up in courts and shuttering the new execution chamber at San Quentin State Prison that has never been used.
"Our death penalty system has been - by any measure - a failure", Newsom will say. "The intentional killing of another person is wrong".
"Governor Newsom has demonstrated great courage and leadership in ending the cruel, costly, and unfair practice of executing prisoners", said Alison Parker, US managing director at Human Rights Watch.
However, in 2012 and again in 2016, Californian voters rejected ballot measures aimed at abolishing the death penalty.
Among those waiting on death row is Luis Bracamontes, an illegal immigrant who killed two law enforcement officers and said in court, "The only thing I [expletive] regret is I only killed two;" and Alberto Hinojosa Medina, who stabbed 21-year-old UCLA student Andrea Del Vesco 19 times in her apartment in Westwood in 2015 before setting the apartment on fire.
Newsom added, however, that he won't tolerate Trump continuing his attacks on California. "It has discriminated against defendants who are mentally ill, black and brown, or can't afford expensive legal representation", Newsom said in prepared remarks he is expected to deliver Wednesday morning.
President Donald Trump said Newsom was "defying voters" in halting the death penalty for "stone cold killers".
The order will also immediately close the execution chamber at San Quentin and states that the directive "does not provide for the release of any individual from prison or otherwise alter any current conviction or sentence", according to Newsom's office.
While campaigning for a measure to repeal the death penalty in 2016, he told The Modesto Bee editorial board he would "be accountable to the will of the voters", if he were elected governor.
Executions have increasingly been the domain of red states, thanks largely to Texas's dominance in capital punishment.
Newsom may have a point to at least looking into the state's approach to the death penalty.
At that time, Newsom said he understood that the issue "raises deeply felt passions on all sides" but he believed that Americans ultimately would look back on the death penalty "as an archaic mistake".