By Aaron Saldanha
Dec 19 - Australian shares rose on Tuesday, as firmer commodity prices supported mining stocks and optimism around U.S. tax reform bolstered global investor sentiment.
Wall Street indexes hit record closing highs on Monday on rising optimism about lower corporate tax rates as the Republican tax bill moved closer to passing.
Republican U.S. Senator Susan Collins said on Monday she would vote for the tax overhaul, which her party's leaders hope to push through Congress this week, all but ensuring its passage.
"We have got an M&A cycle going through a number of sectors, it is really hard to see the market fall," said Mathan Somasundaram, a market portfolio strategist at Blue Ocean Equities. "The U.S. is going up, they have got tax cut optimism playing through...downside risk is very limited in the short-term."
The S&P/ASX 200 index .AXJO was up 0.5 percent, or 29 points, at 6,067.9 by 0054 GMT. The benchmark rose 0.7 percent on Monday.
Mining heavyweight BHP Billiton's shares rose as much as 0.9 percent to their highest in more than a month on strong nickel prices.
Benchmark nickel on the London Metal Exchange hit three-week peaks on Monday after China boosted expectations of higher demand by pledging to cut export taxes on some steel products, but sizeable inventories capped gains.