Jefferson wanted new hope and change for the people. He was an antifederalists who wanted the size of the federal government to be smaller, therefore, making the rights of the people greater. He expanded the right to vote, still mostly white men but they didn't have to own land which was a big change.
Election of 1800
Jefferson stuck to a strict constitution idea. He took his duties and correlated them with the Constitution. He didn't like the idea of implied power and this viewpoint was shown in the Louisiana Purchase in 1803.
The Louisiana Purchase was between the US and the French. Napoleon began a war in Europe, he saw no purpose for the land they held. Therefore, Jefferson went over and claimed this land and was bought for $15 million which was a lot of money back then. When taking this land, he went against his nature. The Constitution never stated that a President could go and take land, however, that's exactly what he did.
Lewis and Clark
In 1800, Jefferson ran against John Adams with Aaron Burr, who was his Vice President candidate. This shows the importance of the 12th Amendment because at the time the majority of the votes won and they had tied. It took 36 ballots in the House of Reps before Jefferson named the winner.
In the last days of the presidency, Adams appointed many federal judges to fill positions created by the Judiciary Act of 1801. Democratic-Republicans were outraged by the appointment of these "midnight judges," so Madison did not deliver the forms. This started the Marbury v Madison case, which outlined the powers of the Judicial Branch through John Marshall's constitutional judgement.
Jefferson believed in the importance of establishing an American presence in the new land from the Louisiana Purchase before the Europeans did. In 1804, President Jefferson appointed his personal secratary Meriwether Lewis along with William Clark, as the leaders of the western expedition.