In the
1905 general election, Hindmarsh stood as an IPLL candidate for Parliament in the
Newtown electorate. Of the four candidates, he came a distant last. In the
1911 general election, he was elected in
Wellington South as a candidate for the
original Labour Party in the second ballot. Hindmarsh was one of four Labour candidates elected in 1911, he was assisted in his campaign in Wellington South by two future Labour MPs,
Jim Thorn and
Walter Nash who were delighted at the party's success. In the following year, 1912, the party was relaunched as the
United Labour Party, with Hindmarsh still a member. In 1913, the United Labour Party itself agreed to merge with the
Socialist Party to form the
Social Democratic Party, but Hindmarsh believed that the resulting party would be too extreme. Hindmarsh chose became one of a group of United Labour loyalists who remained outside the Social Democrats, forming a loosely organised "remnant" faction. In July 1915, when the Social Democrats and the United Labour remnant (along with a labour-aligned independent) agreed to form a united caucus, Hindmarsh was selected as the groups chairman. One month later a
national coalition government was established in response to the severity of
World War I. The leader of the Liberal Party, Sir
Joseph Ward, invited Hindmarsh to be a member of the cabinet (potentially as
Minister of Justice) in the national ministry as the representative of the Labour Party. However, Hindmarsh declined the offer and the Labour caucus decided to maintain its independence by not joining the national ministry. With Ward joining the national ministry as
Minister of Finance and the Liberal Party being now part of the government this left Labour as the largest party not in government. Contrary to convention Hindmarsh was not officially recognised as the
Leader of the Opposition with Ward still retaining the title, albeit in name only. In July 1916, most of the caucus agreed to establish the modern
Labour Party — Hindmarsh was chosen to remain the new party's parliamentary leader during its period of establishment, a position he held until his death. While occupying the position of chairman, Hindmarsh was noted to be a man of great personal attraction and was easily able to establish friendships, even when differing opinions were concerned. This was of great benefit in his position as the recently formed Labour Party had many individuals with both differing personalities and clashing ideas. The addition of more radical Labour MPs like
Harry Holland and
Peter Fraser to the caucus (both via by-elections in 1918) Hindmarsh's ability to manage Labour's MPs became more difficult, admitting that he found the pair to be "wild-eyed". This led to speculation he may have fallen out with them as time went on. One of the largest policy disagreements he had with more radical Labour MPs was conscription. Hindmarsh differed from most of his party colleagues by not opposing conscription and two of his sons fought in the war. He clarified his stance by stating "I do not object to conscription... [but] the State has a duty to the individual". When Labour MP
Paddy Webb was arrested in May 1917 for sedition, by making an anti-conscription speech at a West Coast coal mine, there was speculation that the pro-conscription Hindmarsh might also be apprehended merely by association to Webb. Though this was not to be the case. ==Death==