FL. Sen.: Could Grayson declare a third-party candidacy if he loses the primary?

[UWS]

Alan Grayson and Patrick Murphy sound to hate each other, Murphy was once a Republican, voted in favor of the construction of the Keystone XL pipeline and was implicated in a sort of commitee that investigated on the Benghazi attack in 2012 in which Hillary Clinton was indicted, all of which would not please a great part of the Democratic base. The Democratic establishment is mistreating Grayson just like the Republican establishment did to Trump during the GOP primaries. In addition, as the effects of the Sanders Revolution are still being felt, a part of Bernie Sanders supporters still sound unlikely to vote for Clinton and angry towards the establishment while Murphy is closer to Clinton than Sanders. Could Alan Grayson declare a third-party candidacy if he loses the Democratic nomination?