In Parliament, though a steady supporter of the Reform Party, Mr. Howland was by no means demonstrative in enforcing his views, and was doubtless valued as a party man chiefly because of his respectability and personal influence. When the Reform Party came into power in April, 1862, under the leadership of the Hon. John Sandfield Macdonald and Louis Victor Sicotte, Mr. Howland was offered the post of Minister of Finance, which he accepted and held for a year, when he was succeeded by the Hon. Luther H. Holton in the Macdonald-Dorion Cabinet, which was then formed. In that Cabinet Mr. Howland was assigned the office of Receiver-General. He held this position until the defeat of the Government in 1864. He was not a member of the Coalition Government as formed in June of that year, and consequently was not present either at the Charlottetown Convention, which assembled on the 1st of September, or at the famous Quebec Conference that met on the 10th of the following month, at which, during eighteen days' deliberation, the "Seventy-two resolutions" were agreed to. He was, however, an active and most influential supporter of the Reform wing of the Coalition; and on the elevation of the Hon. Mr. Mowat to the Bench in November, 1864, he succeeded that gentleman as Postmaster-General, and became a member of the Executive Council. He continued to be Postmaster-General until the retirement of the Hon. Alexander T. Galt in August, 1866, when he succeeded the latter as Finance Minister. This office he held till the Union, when, on the formation of the first Dominion Government, on the 1st of July, 1867, he was appointed a member of the Privy Council, and Minister of Inland Revenue.