Here is a Joint resolution for amending the Constitution, as it passed the Senate.  There were six negative votes.  “It is believed that the requisite two-thirds vote will be secured in the House for this measure.”

“It is with devout thanksgiving to God, and emotions of joy which no language can express, that we announce to our readers the passage through the U.S. House of Representative, on Tuesday, last, of the proposed; amendment of the Constitution, in concurrence with the Senate, and the requisite two-thirds vote, abolishing and prohibiting slavery in every part of the republic!  It is the greatest and most important event in the history of congressional legislation. It is better than all the military and naval victories of the war.”

Here is a letter from Wendell Phillips, and then an article from the Anti-Slavery Standard, indicating some of the arguments which are current as members discuss the continuation of the Society, now that the ratification of the Abolition Amendment is expected.