"… When news of the [Louisiana] purchase reached the United States, President [Thomas] Jefferson was surprised. He had authorized the expenditure of $10 million for a port city, and instead received treaties committing the government to spend $15 million on a land package which would double the size of the country. Jefferson’s political opponents in the Federalist Party argued that the Louisiana purchase was a worthless desert, and that the Constitution did not provide for the acquisition of new land or negotiating treaties without the consent of the Senate. What really worried the opposition was the new states which would inevitably be carved from the Louisiana territory, strengthening Western and Southern interests in Congress, and further reducing the influence of New England Federalists in national affairs. President Jefferson was an enthusiastic supporter of westward expansion, and held firm in his support for the treaty. Despite Federalist objections, the U.S. Senate ratified the Louisiana treaty in the autumn of 1803.…"
Source: National Park Service