The primaries now choose the candidates for president, but this was once the job of which of these groups

In the early 19th century, the ruling political party was the Democratic-Republicans. They selected their candidate through a vote of their members in Congress. This system let them control the White House for 20 years. Then the rivalry of John Quincy Adams and Andrew Jackson. divided the Democratic-Republicans into two after the 1824 elections and became Democrats and Whigs.