William Edmund Newton Sinclair (1873-1947) was a Canadian politician.

In the 1917 federal election on conscription (see: Conscription Crisis of 1917), Sinclair ran on as part of the anti-conscription "Laurier Liberals" but was defeated. The 1917 Canadian federal election was held on December 17, 1917. ... The Conscription Crisis of 1917 was a political and military crisis in Canada during World War I. Background At the outbreak of war in 1914, over 30 000 volunteers joined the army, far more than expected. ... Prior to the 1917 federal election in Canada, the Liberal Party of Canada split into two factions: the Laurier Liberals, who opposed conscription of soldiers to support Canadas involvement in World War I and who were led by former Prime Minister Sir Wilfrid Laurier; and the Liberal Unionists who...

He was later appointed to the Legislative Assembly of Ontario as a candidate of the Ontario Liberal Party. He ran for the leadership of the party in the 1922 leadership convention, but lost to Wellington Hay. Hay resigned following a disastrous election result, and Sinclair served as interim leader of the Ontario Liberal Party from 1923 to 1930. He was interim leader for that length of time (and through the elections of 1926 and 1929) because of the party's state of disorganization and inability to hold a proper leadership convention. The Ontario Legislature Building at Queens Park The Legislative Assembly of Ontario, is the legislature of the Canadian province of Ontario. ... The Ontario Liberal Party is a centrist provincial political party in the province of Ontario, Canada. ... Ballot-by-ballot results of leadership races in the Ontario Liberal Party. ... Francis Wellington Hay (1864-1932) was a grain merchant and Canadian politician. ... An interim leader, in Canadian politics, is a party leader who is appointed by the partys legislative caucus or the partys executive to temporarily act as leader when there is a gap between the resignation or death of a party leader and the election of his or her... The Ontario Liberal Party is a centrist provincial political party in the province of Ontario, Canada. ... The Ontario general election, 1926 was the seventeenth general election held in the Province of Ontario, Canada. ... The Ontario general election, 1929 was the eighteenth general election held in the Province of Ontario, Canada. ... In Canadian politics, a leadership convention is held by a political party when the party needs to hold an election for leader due to a vacancy or a serious challenge to the incumbent leader. ...

The Liberals remained at the 14 seats they had in 1926, and dropped to 13 seats in the 1929 election. Sinclair initially decided to run for the permanent leadership in 1930, but because of the party's failure to make gains during his tenure, he attracted little support, and withdrew before balloting began. He remained Leader of the Opposition until the 1934 election because the newly-elected leader, Mitchell Hepburn, did not have a seat in the provincial legislature. The Leader of the Opposition in Ontario is usually leader of the largest party in the Ontario legislature which is not the government. ... The Ontario general election, 1934 was the nineteenth general election held in the Province of Ontario, Canada. ... The Honourable Mitchell Frederick Hepburn (August 12, 1896 - January 5, 1953) was Premier of Ontario, Canada, from 1934 to 1942. ...

In the 1945 federal election, Sinclair was elected to the Canadian House of Commons for the Liberal Party of Canada. He died in office in 1947. The Canadian parliament after the 1945 election The Canadian federal election of 1945 was the 20th General Election in Canadian history. ... The House of Commons (French: Chambre des communes) is a component of the Parliament of Canada, which also includes the Sovereign (represented by the Governor General) and the Senate. ... The Liberal Party of Canada (French: Parti libéral du Canada) is Canadas largest political party. ...