* TSX rises 47.89 points, or 0.39 percent, to 12,329.01 * Seven of 10 main index sectors advance * Energy sector gains 0.9 percent By John Tilak TORONTO, Dec 18 (Reuters) - Canada's main stock index rose on Tuesday - led by energy stocks on firmer oil prices - as optimism swelled that U.S. budget talks to avoid the "fiscal cliff" were making headway. The differences between congressional Republicans and the White House over how to prevent tax hikes and spending cuts due to kick in early in 2013 narrowed significantly after new proposals were seen from President Barack Obama and Republican House Speaker John Boehner. "There seems to be between the two leaders some rapprochement, giving hopes of some sort of agreement coming up," said John Ing, president of Maison Placements Canada. But there may not be a quick resolution to the crisis, he added. "While there seems to be a lot of posturing and movement, whether that's enough remains to be seen." At midmorning, the Toronto Stock Exchange's S&P/TSX composite index was up 47.89 points, or 0.39 percent, at 12,329.01. Seven of the 10 main sectors on the index were trading higher. The energy sector, up 0.9 percent, played the biggest role in leading the market higher, lifted by a 0.6 percent rise in oil prices. In the group, Athabasca Oil Corp rose 4.5 percent to C$10.77, and Niko Resources Ltd was up 2.9 percent at C$10.37. Financials gained 0.6 percent, while the materials sector, which includes mining stocks, slipped 0.5 percent, tracking a decline in gold prices.