Most of the debate in the first few weeks concerned the revision of the Virginia Plan. The Plan "corrected" the inequality that the "one state, one vote" notion inflicted upon the large states (and those, like the Southern states, that hoped to be large soon).
Most of the details could certainly be worked out. Issues like fugitive slaves, export taxes, and import taxes were minor, when compared to the really big issue facing the Convention: representation.
Quite frankly, the small states would never agree to a purely representational form of government. They foresaw the annexation of small, ineffective states as the populations of the large states continued to grow and their influence waned. Some, like the Delaware delegation, were instructed to leave the Convention if equal suffrage in the legislature was compromised. Large states felt the equal suffrage system to be inherently unfair, and were going to do everything they could to abolish it. Today, a conflict between the big and small states seems odd. Conflicts between states are now generally regional and regardless of size. But at the Convention, size, or anticipated size, was one big dividing line.
The intensity of feelings of the two sides were surprises to the others - Madison and the Big State faction thought the inequality of equal suffrage to be so patently unfair that the small states would naturally accede. The small states, used to the status quo, were surprised at how forceful the big states were about proportionality, seeing that the Congress had operated so long under the equal suffrage rule.
The subject of suffrage in the houses of the legislature proposed in the prevailing Virginia Plan came to a debate on June 9, 1787. Threats to dissolve the Convention, and, indeed, the Union, flew from one side of the issue to the other. Fortunately, when the convention adjourned that day, it did so on a Saturday evening, allowing heads to cool and deals to be made that Sunday for presentation to the Convention on Monday. On June 11, Roger Sherman of Connecticut rose on the floor and proposed:
"That the proportion of suffrage in the 1st. branch should be according to the respective numbers of free inhabitants; and that in the second branch or Senate, each State should have one vote and no more."
Sherman was very well-liked and well-respected among the delegates, and spoke more in the Convention than anyone except Madison. In his time, he was a leader, respected by political friend and foe alike. His opinion carried weight. He had advanced an idea such as this as far back as 1776, when it was considered too radical to be taken seriously. This time, it not only was taken seriously, but Sherman's voicing of his compromise may have saved the Convention from doom.
At first, Sherman's plan failed and was rejected. For several weeks, and through the debate on the New Jersey Plan, his idea lay dormant until June 27 and June 28, 1787, when Marylander Luther Martin rose to speak in favor of the Compromise - his speech, long, rambling, and generally disagreeable, seemed to sound the death knell for the idea. Representation in the lower House of Congress was firmly cemented. The small states were firm in the desire for equal suffrage in the Senate. The debates continued and the big states eventually deferred to the small ones: on July 16 and July 23, the Senate we know today was finally agreed to.