OTTAWA (Reuters) - Canadian Prime Minister Justin Trudeau will announce on Monday that he intends to step down as Liberal leader but he will stay on in his post until the party has chosen a replacement, CBC News reported, citing sources.

Trudeau, under heavy pressure from Liberal legislators to quit, is due to hold a news conference at 10:45 am (1545 GMT) on Monday.

A source familiar with Trudeau's thinking told Reuters on Sunday that the prime minister was increasingly likely to announce he intended to step down.

If Trudeau left immediately, it would leave the party without a permanent head at a time when polls show the Liberals will badly lose to the official opposition Conservatives in an election that must be held by late October.

But waiting for the party to hold a leadership contest means Trudeau could still be in office for months, as U.S. President-elect Donald Trump takes office threatening to impose tariffs that would cripple Canada's economy.

An increasing number of Liberal parliamentarians, alarmed by a series of gloomy polls, have publicly urged Trudeau to quit. Polls suggest that no Liberal leader could take the party to victory over the Conservatives after nine years in power.

(Reporting by Ismail Shakil in Ottawa; Editing by David Ljunggren)