What action by John Adams is believed to have cost him reelection?

The action that is widely considered to have cost John Adams his reelection is sending a peace commission to Paris. This decision was made during the Quasi-War with France, a messy undeclared war fueled by tensions between the two nations. Many in Adams's own Federalist Party thought that a stronger stance against France was necessary. By opting for diplomacy and peace, Adams went against the prevailing sentiment among many Americans who were more hawkish and desired a show of military strength.

Adams's decision to pursue peace rather than escalate the conflict was seen by many as a sign of weakness and led to significant criticism from his party and his opponents. This ultimately contributed to his loss in the election, as it alienated segments of his party and diminished his support among the electorate, who were more inclined towards a confrontational approach against France.

In contrast, the other options listed have different implications and contexts. The Alien and Sedition Acts, while unpopular, were actually enacted prior to the election and were part of the larger political strategies of the time. Signing the Treaty of Ghent ended the War of 1812 and is associated with James Madison, not Adams. The Louisiana Purchase was a significant expansion under Thomas Jefferson's administration. Therefore, the peace