Sobel Wiki is on the Liberty Party, the oldest major political party in the United States of Mexico. The Liberty Party was formed in opposition to Alexander Hamilton's Continentalist Party in the late 1790s in the quasi-independent state of Jefferson. Although Robert Sobel never explicitly linked the formation of the parties to the outbreak of the Trans-Oceanic War, the timing makes it clear that Hamilton's actions during the war precipitated the partisan split in the settlement.
As I've noted previously, the foundation of Jefferson was the Sobel Timeline counterpart to the settlement of Canada by the United Empire Loyalists in our history. Having lost the Rebellion, the most intransigent Patriots chose to leave the Thirteen Colonies (as they now were again) to establish an independent settlement. They chose the province of Tejas in New Spain as their final destination, and life was sufficiently hard there that it was only continued immigration from the British colonies that allowed the new settlement to survive.
Sobel makes it clear that there was no compelling reason for the Jeffersonians to rebel against Spain. The government of King Carlos IV had no interest in affairs in Spain's New World colonies, and as far as we can tell, the Jeffersonians were left alone by administrators in Mexico City and San Antonio. And yet, rebel they did. Specifically, according to Sobel, the Jeffersonians used the outbreak of war between Spain and Great Britain in 1795 as an excuse to rise up against Spanish rule and seize control of as much of Spanish Tejas as they could manage. They were able to get away with it because the rest of Spain's New World colonies rose up in rebellion after the Spanish Bourbons were removed from the throne and a member of the Protestant House of Hohenzollern set in their place in the 1799 peace settlement.
The decision to launch a rebellion against Spanish rule was made by Hamilton himself, who resigned from the office of co-Governor of Jefferson to lead an army of conquest against San Antonio and the other Spanish settlements in Tejas. The object apparently was to seize as much land as possible to ensure that the cotton boom of the 1790s kept booming. This of course would mean establishing a slave-based cash crop economy in Jefferson like the one that was already established in the Southern British colonies (by now organized into the Southern Confederation). And this, ultimately, was the issue that brought partisan politics to Jefferson: Hamilton and his allies wanted Jefferson to become a slave society, while his opponents believed that slavery was contrary to the spirit of the Declaration of Independence. And so Hamilton's opponents called themselves the Liberty Party.
As we know from our own history, the profits from the cotton boom were great enough to override most peoples' moral scruples, and so it proved in Jefferson. Slavery was immensely popular; so much so that, from what Sobel tells us, the Libertarians never formed a single government for all of Jefferson's existence as an independent state -- which admittedly only lasted until 1820. After that, Andrew Jackson oversaw the merger of Jefferson and the republic of Mexico to create a sort of Greater Jefferson that he called the United States of Mexico. Since participation in the national government of the U.S.M. was restricted to English-speakers, it was the Jeffersonian parties that contested the new country's national elections. And again, the Libertarians kept losing to the Continentalists, now led by Jackson.
During the sixty-year period that one might call the First Republic (though Sobel never uses the term), from 1821 to 1881, the Libertarians only managed to win two out of nine national elections. After the restoration of republican rule in 1902, the Libertarians again looked set to remain a perpetual opposition party, losing the elections of 1908 and 1914. But then, in 1920, the issue of slavery once again came to the fore. The Libertarians ran a military hero, General Emiliano Calles, as their candidate, and his great personal popularity allowed them to win at last. However, in order to abolish slavery, Calles had to make a devil's bargain with the real ruler of the U.S.M., Douglas Benedict, head of the One Big Zaibatsu that ruled the Mexican business world and controlled the Mexican economy: Kramer Associates.
Ever since the rise of K.A. in the 1860s, the company's financial control of the Mexican election system had made them the natural enemy of the Liberty Party. And so they remained, until Calles and Benedict reached their gentleman's agreement on 30 April 1920. Calles and the Liberty Party would leave the company alone, and Benedict would use his financial control of the Mexican government to ensure the abolition of slavery. And so it was done.
With K.A. now allied to the Libertarians, the U.S.M.'s other major party, the United Mexican Party, turned against the company. President Pedro Fuentes of the U.M.P. spent six years attempting to bring the company under control, to no avail. With K.A.'s help, the Libertarians were able to elect Senator Alvin Silva president, and under Silva the policies of the two parties completed their reversal. Now it was the Libertarians who supported an aggressive foreign policy, and the U.M.P. who agitated for domestic reforms. Silva remained in power until 1950, leading Mexico into war against Japan and the United British Empire, before being overthrown in a military coup that brought an end to the Restored Republic and returned Mexico to dictatorship.
So it was, in one of the many ironies with which the Sobel Timeline abounds, that the Liberty Party ushered in a dictatorship that was still in power when Sobel was writing in 1971.