He served for 15 years as an associate justice of the Massachusetts Supreme Judicial Court, all the while running unsuccessfully as a Democrat for governor.

His brief periods of ascendancy, however, resulted in no substantive Democratic-supported reforms, since the dominant Whigs reversed most of the changes enacted during his terms.

An opponent of the extension of slavery, he split with longtime friend John C. Calhoun over that issue, and eventually left the party for the Free Soil movement.

[2] Morton received his early education at home, and was placed at age fourteen in the academy of Reverend Calvin Chaddock at Rochester, Massachusetts.

[8] In 1808 Governor James Sullivan offered him the post of district attorney for Bristol County, but he demurred because the office was still held by his teacher, Judge Padelford.

[11] Morton was nominated by the Democratic-Republicans to run for Congress in 1814, but lost by a wide margin to Laban Wheaton in what was then seen as a strongly Federalist district.

[8] Morton was personally opposed to slavery, but did not often let it inform his political decisions until later in life; he preferred instead to focus his efforts on other priorities.

[17] Morton disagreed with this trend (calling the National Republicans "aristocratic"), preferring Jacksonian-style Democracy instead, and refused to stand for election as governor in 1825.

He was, however, prevailed to run again for lieutenant governor, and he won the post, serving under Levi Lincoln Jr., who had been nominated by both the Republicans and a rump Federalist coalition.

Morton was unhappy with what he termed Whig elitism (he accused Lincoln in 1830 of being a "tool of monied aristocracy"), and resigned the lieutenant governorship.

[18] Lincoln promptly appointed Morton as an associate justice of the Massachusetts Supreme Judicial Court (SJC), a post he would hold until 1840.

Morton wrote the decision favoring the defendants, pointing out that if the state was going to grant an exclusive right, it had to do so explicitly, and it had not done so in this case.

[26] The third faction, which successfully controlled the party apparatus in its early years, was headed by David Henshaw, who had split from the John Quincy Adams camp over political aspects of the bridge controversy.

[27] Henshaw was the principal party organizing force, while Morton became a perennial gubernatorial candidate, running for the office each year from 1828 to 1843.

[13][28] The party was supported in its organizing efforts by Morton's friend John Calhoun, who served as Vice President under Adams and Jackson.

[34] Morton was sufficiently disheartened by his repeated failures that he considered abandoning his quest for the governorship in 1832; Henshaw convinced him to soldier on.

Both Whigs and Democrats (including Morton) had avoided the issue in pursuit of other political objectives, but abolitionists began regularly requesting formal statements from candidates for office on the subject.

[41] David Henshaw resigned from the politically important post as the collector of the Port of Boston in 1837, starting a struggle within the party for this valuable patronage plum.

The Whig legislature had passed a bill promoted by temperance activists that banned the sale of liquor in quantities less than 15 US gallons (57 L); this effectively outlawed service over a bar.

[48] Proposals such as reductions in the poll tax and the number of capital crimes were defeated, but the Democrats were able to introduce some fiscal discipline and produced the first budget surplus in some years.

The Liberty Party hoped to use its position in the balance of power to control the outcome, but a single Whig defector in the vote to fill the senate led to a Democratic majority in the chamber.

[53] Morton once again called for a series of reforms, repeating those from 1840, and including a proposal to transfer the tax burden from real to personal property.

[60] After an acrimonious state convention in 1847 (in which the Henshaw faction refused to allow platform items opposing slavery), Morton quit the party for the burgeoning Free Soil movement.

[61] Morton would refuse to support the Democrat-Free Soil coalition that in 1850 saw the election of Democrat George S. Boutwell as governor and Free Soiler Charles Sumner as U.S.

[62] In 1848 Morton was invited by Martin Van Buren to run as the vice presidential nominee on the Free Soil ticket.