Like many other able young lawyers, Jay took an active part in the proceedings that resulted in the independence of the United States, identifying himself with the conservative element in the Whig or patriot party.
Until 1832 there was only one party in the state, the Democratic, but the question of nullification caused a division that year into the (Jackson) Democratic party and the State's Rights (Calhoun Democratic) party; about the same time, also, there arose, chiefly in those counties where the proportion of slaves to freemen was greater and the freemen were most aristocratic, the Whig party.
The landing of the Pretender in Scotland (1715), and the defeat of a portion of his army which had advanced to Prestona defeat which was the consequence of the apathy of his English supporters, and which was followed by the complete suppression of the rebelliongave increased strength to the Whig government.
After a period of work in Holland he betook himself to England, where his treatise on lettres de cachet had been much admired, being translated into English in 1787, and where he was soon admitted into the best Whig literary and political society of London, through his old schoolfellow Gilbert Elliot, who had now inherited his father's baronetcy and estates, and become a leading Whig member of parliament.
He soon found another constituency at Oxford, and upon the formation of Lord Aberdeen's coalition ministry became president of the Board of Trade, although debarred by the jealousy of his Whig colleagues from a seat in the cabinet.
In the first pages of this marvellously minute record of a busy life we find him depicting the decline of Whig credit and complaining of the cold reception accorded him by Godolphin, whose penetration had doubtless detected the precariousness of his allegiance.
The vigorous course of the president towards South Carolina, however, led him, after 1833, to act more and more with the opposition which presently became the Whig party; but he was never at heart a Whig, at least as Whig principles came later to be defined, and his place is with the Democrats of the Calhoun school.
He was a friend of the Whig leaders Stanhope and Sunderland, took a share in defeating the Jacobite conspiracy of Bolingbroke on the death of Queen Anne, and supported the passing of the Septennial Act.
Members gradually united with other opponents of Jacksonian Democracy in forming the Whig party.
Marcy in 1833-1839, was a member of the New York Assembly in 1842, in 1844 and in 1845, being speaker in 1845; mayor of Utica in 1843, and in 1852 was elected governor of the state over Washington Hunt (1811-1867), the Whig candidate, who had defeated him in 1850.