Question

What caused Jefferson and his party to change their approach to governing

Answer 1

There was a fear of a civil war between Federalists and anti-Federalists on the Election of 1800. If Jefferson changed his beliefs that there's a triumph within the "Strongest government of the Earth", and tried to unite all Americans regardless of political belief, he would not only put freedom at sake, but he would unite a whole country. 

Answer 2

The presidential campaign of 1800 that pitted Jefferson and Aaron burr against John Adams and Charles cotesworth was bitterly consented