Crawford had built a homemade X-ray machine that used deadly amounts of radiation to kill targets and could be detonated remotely, ABC news reports.
The FBI said the device would have been both "functional" and "lethal". They said Crawford had called his design "Hiroshima on a light switch".
Obama was identified as the "political figure" the pair were targeting. They also planned to attack a Muslim organisation.
On the day of the Boston Marathon bombings, Crawford allegedly sent a text message saying: "Obama`s policies caused this".
"He directed the [government] to start bringing [Muslims] here without background checks," Crawford wrote.
"They don`t have to follow any laws, and this administration has done more to enable a government sponsored invasion than the press can cover up."
The FBI said Crawford was a member of the Ku Klux Klan and they began investigating him last year after he allegedly inquired about technology that could kill "Israel`s enemies while they slept".
Crawford, who investigators say spent months building the X-ray machine, recruited Feight to his kill plot after the pair met while working at GE.
Both men have been charged with conspiracy to provide material support to terrorists, namely through use of a weapon of mass destruction
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