The Congress was to determine the choosing of___
who were to give their votes for president

The Congress was to determine the choosing of Electors who were to give their votes for President.

Explanation:

In the process of election or choosing a President, Congress has an important part to play in determining the correct procedure of the election process. While each state may choose its own representatives for the Electors, it is upon the Congress to select the final electors.

Choosing an elector is one major step in selecting the President for they are the people's representatives in choosing the leader of the country. So, in each state, potential candidates were chosen for the role of the electors. Then, the voters of the state will vote among the chosen candidates for their representative in the House. Then, after that, the Congress will decide who are to be the Electors.  And these elected Electors will give their votes to select the President of the country.

whole lotta ptsd going on

the answer is suffrage