Is it because of the debate?

Romney is on rise obviously. However, I started half-doubting if it is really due to the debate on October 3rd. Of course, a lot of people say Obama lost and Romney won. However, is his lead really due to that debate? Let's look at the following graph offered from RealClearPolitics.com Romney started rising well before the debate. He hit the bottom around September 27.His rate started rising on September 30. Before the debate, Obama's popularity was also on rise but Romney's slope was much steeper. After the debate, Obama's rate started falling very drastically while Romney has kept on the rising track. My conclusion: Obama's support is falling due to the debate: it seems so. What about Romney? I think it is just a reactive bounce due to his weak performance in September. Since he was very weak in September, the Republicans felt threatened and started gathering around Romney. According to Romney, there are 47% who vote for him whatever he does; there are also other 47% who vote for Obama whatever he does. I think he is right. Currently neither strongly gains in the rest 6%. If only Romney surge is very stable until November, I may believe Romney is leading because of the October 3rd debate.