Former Trump chief strategist Steve Bannon slammed UN ambassador Nikki Haley's decision on Tuesday to announce her resignation, calling it "suspect" and "horrific," and that it overshadowed positive news that Trump and the Republicans need to build support going into midterms, according to Bloomberg.

"The timing was exquisite from a bad point of view," Bannon told Bloomberg News Editor-in-Chief John Micklethwait on Wednesday at the Bloomberg Invest London forum. "Everything she said yesterday and everything she said about stepping down could have been done on the evening of November 6. The timing could not have been worse. "

Haley's announcement, according to Bannon, took White House officials by surprise - and distracted attention from Brett Kavanaugh's first day as a justice on the Supreme Court, along with headlines over the lowest US unemployment rate in five decades. Haley's decision undermines Trump's message to Republican voters, said Bannon.

In the Oval Office on Tuesday, Trump said Haley told him six months ago she wanted a break after spending two years in the post. She’ll continue in her role until year-end. Haley said Tuesday that she was ready for a break after two terms as South Carolina’s governor and two years at the United Nations. -Bloomberg

Bannon also says that he took Haley at her word that she has no political aspirations - particularly when it comes to running against Trump in 2020. She says that she looks forward to campaigning for Trump in two years. That said, Bannon calls Haley "ambitious" and "very talented," though he said so using a backhanded compliment.

"I think she is incredibly politically ambitious," Bannon added. "Ambitious as Lucifer but that is probably...I am probably taking Milton out of context."

Trump defended the timing of Haley's departure on Wednesday, saying "there's no good time" for her to have announced her resignation - and that if she'd waited until after midterms, it would have raised questions as to whether her motive was based on the results.