At noon AEDT on Tuesday, the benchmark S&P/ASX200 index was down 42.9 points, or 0.53 per cent, to 8,121.70, while the broader All Ordinaries was down 44.9 points, or 0.53 per cent, to 8,377.90.
The ASX was a sea of red, with all sectors trading lower as traders preferred to sit out the uncertainty over the next couple of sessions.
The RBA is widely expected to keep interest rates on hold at 4.35 per cent later on Tuesday, but investors will be closely watching the board's statement and the RBA governor's comments for any changes in its likely stance on interest rates.
Globally, investors are also wary of the outcome of the US election on Wednesday AEDT, with opinion polls suggesting the Republican candidate Donald Trump and Democratic rival Kamala Harris are in a photo finish in the race to the White House.
In the local market, losses were led by heavyweight financial and consumer stocks, while technology shares also traded deep in the red.
Each of the four major banks were trading about 1 per cent lower, while miners also followed suit with BHP, Rio Tinto and Fortescue Metals down between 0.3 per cent and 0.5 per cent.
Consumer staples were among the worst-performing sectors, with Coles and Woolworths both down nearly 1.0 per cent each and A2Milk losing 2.7 per cent.
Domino's Pizza Enterprises was among the biggest losers on the benchmark index, after the fast food retail chain announced long-time chief executive Don Meij would step down effective November 6.
Shares in the company hit their lowest level in nearly two months and were trading 7 per cent lower at $31.35.
Meanwhile, the Australian dollar was buying 65.84 US cents, down from 66.06 US cents at Monday's ASX close.