A resolution called for ending the ability to vote for U.S. senators. Instead, senators would get appointed by state legislatures, as it generally worked 110 years ago prior to the passage of the 17th Amendment in 1913.
“We are devolving into a democracy, because congressmen and senators are elected by the same pool,” was how one GOP delegate put it to the convention. “We do not want to be a democracy.”
The most common definition of a Republic is that the head of state is not determined by birth. China is a Republic. So are Germany/France/Italy. The main difference between most Western countries and e.g. China is the presence of a representative democracy.