Question: What was the political party of the president that Eugene V. Rostow served under?

Context articles: Walt Whitman Rostow
Lyndon B. Johnson
United States presidential election, 1912
Eugene V. Debs Cooperative House
Eugene V. Debs Foundation
Socialist Party of Illinois
Joseph Sharts
Eugene V. Rostow
Ben Hanford
J. Mahlon Barnes

Walt Whitman Rostow (also known as Walt Rostow or W.W. Rostow) {'1': ", '2': ", '3': ", '4': "} (October 7, 1916 – February 13, 2003) was an American economist and political theorist who served as Special Assistant for National Security Affairs to US President Lyndon B. Johnson in 1966–1969.
Lyndon Baines Johnson ( ; August 27, 1908January 22, 1973), often referred to as LBJ, was an American politician who served as the 36th President of the United States from 1963 to 1969, assuming the office after serving as the 37th Vice President of the United States from 1961 to 1963.
 A Democrat from Texas, he also served as a United States Representative and as the Majority Leader in the United States Senate.
 Johnson is one of only four people who have served in all four federal elected positions.
The United States presidential election of 1912 was the 32nd quadrennial presidential election, held on Tuesday, November 5, 1912.
 The election was a rare four-way contest.
 Incumbent President William Howard Taft was renominated by the Republican Party with the support of its conservative wing.
 After former President Theodore Roosevelt failed to receive the Republican nomination, he called his own convention and created the Progressive Party (nicknamed the “Bull Moose Party”).
 It nominated Roosevelt and ran candidates for other offices in major states.
 Democrat Woodrow Wilson was finally nominated on the 46th ballot of a contentious convention, thanks to the support of William Jennings Bryan, the three-time Democratic presidential candidate who still had a large and loyal following in 1912.
 Meanwhile, the Socialist Party of America renominated its perennial standard-bearer, Eugene V. Debs.
 It is the last election in which a former, or incumbent, President (Roosevelt) ran for the office without being nominated as either a Democrat or Republican.
 It is also the last election in which an incumbent president running for re-election (Taft) failed to finish either first or second in the popular vote count.
The Eugene V. Debs Cooperative House is a student housing cooperative founded in 1967, one of the 18 cooperative houses which make up the Inter-Cooperative Council at the University of Michigan.
 Debs Cooperative is located at 909 East University Avenue in Ann Arbor, Michigan, and is named for Socialist Party candidate Eugene V. Debs.
 Debs has a reputation for being politically-active, socially conscious, and environmentally-focused.
 House funds go towards maintenance and the purchase of organic food, and members of the house cook vegetarian and vegan meals five nights a week.
The Eugene V. Debs Foundation is a non-profit educational foundation, founded in 1962 “to own, maintain and operate the Eugene V. Debs Home in order to be a memorial to Eugene V. Debs and Theodore Debs".
 During the time since its inception, the Foundation has operated a museum in the historic home of Eugene V. Debs in order to preserve and promote the legacy of the noted union leader, anti-war activist and socialist political leader, Eugene V. Debs.
The Socialist Party of Illinois (SPIL) is a political party in the state of Illinois.
 It was affiliated with the Socialist Party of America.
 It was founded in September 1901, though the grouping met in 1900 at a convention in Chicago and supported Eugene V. Debs for president in 1900.
 It was the successor to the Social Democratic Party of America.
Joseph William Sharts (1875-1965) was an American attorney, political activist, newspaper editor, and novelist.
 Sharts is best remembered as a popular novelist of the first two decades of the 20th Century and as a defense attorney in a number of high-profile political trials, including cases involving Socialist Party of America leader Eugene V. Debs, future Workers (Communist) Party leader C. E. Ruthenberg, and radical clergyman William Montgomery Brown.
Eugene V. (Victor Debs) Rostow (August 25, 1913 – November 25, 2002) was an American legal scholar and public servant.
 He was Dean of Yale Law School and served as Under Secretary of State for Political Affairs under President Lyndon B. Johnson.
Benjamin "Ben" Hanford (1861 – January 24, 1910) was an American socialist politician during the late 19th and early 20th centuries.
 A printer by trade, Hanford is best remembered for his 1904 and 1908 runs for Vice President of the United States on the ticket of the Socialist Party of America, running next to Presidential nominee Eugene V. Debs.
 Hanford was also the creator of the fictional character "Jimmie Higgins," a prototypical Socialist rank-and-filer whose silent work on the unglamorous tasks needed by any political organization made the group's achievements possible — a character later reprised in a novel by Upton Sinclair.
John Mahlon Barnes (1866–1934) was an American trade union functionary and socialist political activist.
 Barnes is best remembered as the Executive Secretary of the Socialist Party of America from 1905 to 1911, during which time he originated the idea of the party's 1908 "Red Special" campaign train on behalf of its Presidential nominee, Eugene V. Debs.