* TSX down 52.31 points, or 0.36 percent, to 14,645.62
* Eight of the TSX's 10 main groups fall
TORONTO, Sept 26 (Reuters) - Canada's main stock index fell on Monday as heavyweight financial stocks led a broad move lower, with only slight gains from weighty natural resource groups offsetting the losses.
Investors globally are focusing on how Republican Donald Trump would fare in a U.S. presidential debate against Democrat Hillary Clinton, which could rank as one of the most watched and highly anticipated political showdowns in U.S. history.
At 10:19 a.m. EDT (1419 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE fell 52.31 points, or 0.36 percent, to 14,645.62. There were two decliners for every gainer.
The most influential weights included Royal Bank of Canada RY.TO , which fell 0.8 percent to C$80.72, and Toronto-Dominion Bank TD.TO , down 0.6 percent to C$57.80. The financials group slipped 0.8 percent.
The energy group was barely higher despite rallying oil prices as the world's largest producers gathered in Algeria to discuss ways to support the market. O/R
TransCanada Corp TRP.TO fell 0.7 percent to C$62.53. One of its units, Columbia Pipeline Group, offered to buy Columbia Pipeline Partners LP CPPL.N for about $848 million in cash.
The materials group, which includes precious and base metals miners and fertilizer companies, added 0.4 percent.
The rest of the index's 10 main sectors fell.
Consumer staples lost 1 percent and discretionary slipped 1.2 percent, with convenience store operator Alimentation Couche-Tard ATDb.TO down 1.6 percent to C$64.29 and Restaurant Brands International QSR.TO off 2.4 percent to C$59.24.
Industrials fell 0.5 percent.
Auto workers in the Unifor union ratified a deal with General Motors Co (NYSE:GM) GM.N on Sunday that will see C$554 million ($421 million) invested in local plants. crude CLc1 prices were up 2 percent to $45.37 a barrel, while Brent LCOc1 added 2 percent to $46.79.
Gold futures GCc1 rose 0.3 percent to $1,341.8 an ounce, while copper prices CMCU3 declined 0.3 percent to $4,841.5 a tonne. GOL/ MET/L
($1 = 1.3161 Canadian dollars)