Why is President John Tyler referred to as a president without a party?

John Tyler (1790–1862) was the first vice president to become president after William Henry Harrison (1773–1841) died only one month into his term. John Quincy Adams, a former president, and many others did not think Tyler should have assumed the full powers of the presidency. In other words, they thought he should merely carry out presidential duties while remaining vice president. Tyler rejected his opponents' views and moved into the White House. In response, his detractors called him "His Accidency," and he never gained much support.
Harrison and Tyler had run for office on the Whig ticket. But Tyler did not really support Whig policies. After Tyler vetoed two bills aimed at creating a national bank, nearly his entire cabinet resigned. He became a president without a party. His party, the Whigs, and the other party, the Democrats, opposed him. He had no chance of winning a second term and withdrew from the next presidential race in mid-1844.