OTTAWA - NDP Leader Thomas Mulcair dropped his party's usual references to low-income Canadians, unions, aboriginals, and human rights in his first speech to his caucus Wednesday.

Instead, Mulcair repeatedly referred to a single group of Canadians he says the Conservative government will abandon in its budget on Thursday.

"The middle class will be left out in the cold," Mulcair declared to his caucus colleagues, seated around him in the historic Railway Room in Centre Block on Parliament Hill.

Only days after being elected NDP leader, Mulcair aimed a Liberal-style attack on the agenda of Prime Minister Stephen Harper.

"If Canada sees no action to boost job creation, if pensions and health care are cut, and Canadians are left footing the bill, then, Mr. Harper, you will have a fight on your hands," he said to raucous applause from New Democrat MPs.

Setting himself up as the alternative to Harper, Mulcair pledged "to reach out...to those who've been abandoned" by the Conservatives.

The speech and Mulcair's pre-emptive strike against the budget got under the skin of Conservative MP Chris Alexander.

"The NDP has already opposed stable, sustainable, and record investments in health transfers, support for seniors - including the largest increase in the GIS (guaranteed income supplement) in over 25 years - and every tax cut and credit introduced for hard-working Canadian families," Alexander told the Commons.

Mulcair didn't get a chance to face Harper in the House of Commons on Wednesday.

Just back from a three-country Asian tour, the Prime Minister didn't attend question period.