[1] He was educated in public schools in Wagga and Yass before purchasing grazing land in Narrabri and West Wyalong; he married Florence Hogarth in 1899, a union which produced no children.

Manning was victorious, narrowly defeating sitting Labor representative Samuel Nicholls by less than 100 votes after preferences from an independent were distributed.

Manning faced controversy during his first term in federal parliament when it was revealed in 1924 that he and fellow parliamentarian farmer William Killen had signed cheques on behalf of the government to the Australian meat industry (in which they both had interests).

Despite the controversy, Manning retained his seat at the 1925 election, defeating Labor candidate and future prime minister Ben Chifley.

In 1926, Manning was a member of the Australian delegation to the League of Nations General Assembly, discussing, among other issues, Australia's administration of the former German New Guinea.