(Adds details, closing market figures, strategist comments) * Canadian dollar at C$22.32, or 81.75 U.S. cents * Bond prices mostly lower across maturity curve By Solarina Ho TORONTO, May 19 (Reuters) - The Canadian dollar retreated against its U.S. counterpart on Tuesday to its weakest level in about a month, as the greenback rallied to a two-week high against a basket of major currencies and helped push crude oil prices down more than 3 percent. The Canadian dollar extended its losses from Monday, ahead of a speech by Bank of Canada Governor Stephen Poloz that had many market participants speculating that Poloz might temper his previous optimism about an improving Canadian economy. But Poloz's speech on Tuesday largely left the Bank of Canada's views unchanged ahead of its monetary policy decision next week. "There was an expectation that perhaps he'd backpedal a little bit on the optimism we got earlier. But we didn't really get that," said Shaun Osborne, chief currency strategist at TD Securities. "It sounded a bit cautious at the margins." The Canadian dollar ended at C$1.2232 to the greenback, or 81.75 U.S. cents, sharply weaker than Friday's Bank of Canada close of C$1.2022, or 83.18 U.S. cents. The loonie traded between C$1.2130 and C$1.2250 on Tuesday. Most Canadian trading floors were closed on Monday for the Victoria Day holiday, when the Canadian dollar saw a substantial retreat and ended at C$1.2159, or 82.24 U.S. cents, according to Thomson Reuters Eikon data. "Given the rebound we've seen from C$1.19 last week, the Canadian dollar didn't look entirely fundamentally justified trading as high as it did," Osborne said. The U.S. dollar, already bolstered by indications the European Central Bank may take more measures to lower euro zone bond yields and boost inflation, was given additional support by unexpectedly better U.S. housing data for April. The greenback's strength, combined with a well supplied global oil market, also pushed the price of crude, a key Canadian export, down sharply, for a fifth straight day of losses. U.S. crude prices fell 3.65 percent to $57.26 a barrel, while Brent crude fell 3.14 percent to $64.18 a barrel. Despite the loonie's losses, it was stronger against almost all its major currency counterparts. Canadian government bond prices were mostly lower across the maturity curve, with the two-year down 9.5 Canadian cents to yield 0.696 percent and the benchmark 10-year sliding 1.04 Canadian cents to yield 1.852 percent. * The Canada-U.S. two-year bond spread was 7.9 basis points, while the 10-year spread was -45.7 basis points. (Reporting by Solarina Ho; Editing by Paul Simao and Leslie Adler)