Green’s Dictionary of Slang

complete, absolute, unswerving, devoted, usu. with regard to politics.

1829		Virginia Herald 28 Mar. 2/3: We all know that of late he has shown a disposition to become ‘a whole hog man,’ but if he can swallow this, he can swallow anything [DA].
1836		D. Crockett Exploits and Adventures (1934) 164: I’m a whole hog temperance man.
1838		P. Hone Diary I 308: Three other thorough whole-hog men [...] have no [...] notion of political honesty [DA].
1867		Newcastle Jrnl 29 Jan. 3/4: The Whole-Hog Reform Demonstration [...] Mr Ernest Jones says they who are not with the whole-hog men must be against them.
1905		Manchester Courier 13 Sept. 2/6: ‘Whole Hog’ Resister.
1912		Congressional Record 1 Jan. 4/2: Whole-hog standpatters are about as scarce as whole-hog progressives [DA].
1927		E. Wallace Squeaker (1950) 17: I believe in the whole-hog method.
1948		Sat. Eve. Post 10 July 68/4: More importantly, by clearing the path for Polk, called by his supporters ‘a whole-hawg Democrat,’ it greased the ways for the Mexican War [DA].