It was Richard's idea; he was the first to put the thing in words and say out loud what most of them were thinking. But, it was too radical for some, so they quit and went home to think about it.
However, since the majority were so sure they would end up doing it, they assigned Tom and four others the job of preparing a formal statement explaining exactly what they were doing and why.
They all got back together a few weeks later. They made some changes to what Tom wrote, and set it aside.
Then they voted on Richard's idea. It passed. John was so excited he told his wife that the day was so special, it
ought to be solemnized with pomp and parade, with shows, games, sports, guns, bells, bonfires, and illuminations from one end of this continent to the other from this time forward forever more.
That was July 2. Here's Richard's idea in his own writing:
Two days later they approved Tom's official statement and explanation of their decision. That night a few hundred copies of Tom's document were printed. Only 25 are still around today. Here's one of them:
Every schoolkid knows about Thomas Jefferson and his masterpiece. Richard Lee is forgotton. And we do exactly what John Adams told us to do to celebrate -- we just don't do it on the day he said.
(you can read more here)