At the founding of America, the Federalists had most control over the government. They were well organized, well funded, and influential. George Washington and Alexander Hamilton put out Federalist agendas. They got the Constitution passed. John Adams was a Federalist as well. But that changed when Thomas Jefferson was elected as the first Democratic-Republican. What followed was a multi-decade reign of the “party of the people”.
1800 marked a hard and emotional fight between Adams and Jefferson. But in the end, the Democratic-Republicans won a clear victory, with Jefferson being elected and the party gaining a 65-38 and 17-15 majority in the House and Senate respectively. By 1806, the party held over 82% of both houses. The Election of 1800 marked the end of the Federalist Party, which would never again hold significant power.
The Democratic-Republicans would reshape the US for the next several decades. Today, their beliefs are most similar to that of the modern Republican Party.