The free- trade tariff of 1846 was passed; and Mr.Dallas, who had been nominated because of his record as a protectionist, was subjected to the humiliation of giving his casting vote as Vice-President in favor of a tariff which was execrated in Pennsylvania, and which was honestly believed to be inimical in the highest degree to the interest of the American manufacturer and the American mechanic.
The Act had no small influence in the overthrow of the Polk administration at the elections for the next ensuing Congress, and in the defeat of General Cass for the Presidency in 1848.

As senator from Michigan, General Cass had voted for the bill, influenced thereto by his Southern associates, for whom he always did so much, and from whom he always received so little.

Pennsylvania was at that time really a Democratic State, but she punished General Cass for his free-trade course by giving her electoral vote to Taylor.
If she had given it to Cass he would have been chosen President.
It was in connection with the tariff agitation of 1846 that Simon Cameron originally obtained his strong hold upon the popular sympathy and support of Pennsylvania.

He was a Democrat; had long been confidential adviser to Mr.Buchanan, and had supported Mr.Polk.
But he was a believer in the doctrine of protection; and as he had aided in carrying Pennsylvania by declaring himself a friend to the tariff of 1842, he maintained his faith.

When the Polk administration was organized, a vacancy was created in the Senate by Mr.Buchanan's appointment as Secretary of State.