President Trump's pick to be chief scientist for the Department of Agriculture (USDA) previously suggested former President Obama wanted to "enslave" his opponents and seemed "happy" after the 2012 attacks in Benghazi, Libya.
CNN's KFile reviewed transcripts of episodes of Sam Clovis's radio show, audio from his radio appearances and blog posts by Clovis, which showed him going after the former president.
"This president is a dangerous person," Clovis wrote in an April 2012 blog post reported by CNN.
"He is dangerous in that he does not have the interests of the nation in mind and is more than willing to do anything to advance an ideology that is absolutely opposed to American exceptionalism."
Having Obama as president for four more years could result in "the total destruction of our Constitutional republic," he wrote.
"He wants to be a dictator and he wants to enslave all who are not part of his regime," Clovis wrote.
"As Althusius advised in the 17th Century, we have a right to throw off imprudent magistrates. The current president certainly qualifies. Vote in November."
In September 2012 during an episode of his online radio program, "Serious Civics with Sam Clovis," Clovis said Obama seemed "happy" following the attacks in Benghazi, Libya.
"This is something that tells you that he is dismissive of the entire affair and in fact, I would even hate to stretch this out but it's almost as if it was intentional," Clovis said during the radio show.
"As if he is happy that these things have occurred."
Clovis admitted that he had no evidence to support his accusations, but he called for his listeners to look at Obama's actions.
"Right after the event, where does he go? He goes and he does an interview on the hip hop guy who is a pimp and on top of everything else," Clovis said.
"The fact that he goes to Las Vegas and essentially just mentions in passing that we've had four Americans killed in Libya under a premeditated orchestrated attack and he doesn't seem to have any more attachment to it than that. This is frightening."
Clovis also said in a 2012 blog post that Obama for over a decade let his publisher carry a biography "that had him born in Kenya."
"Only after beginning his pursuit of public office did he 'correct' the entry," Clovis wrote.
President Trump nominated Clovis —a climate change doubter who was an early supporter of his — to the USDA's top science position in July.
In the role, he would coordinate the department’s research and education policies and ensure the “scientific integrity” of the research done at the department.