OTTAWA - Former Quebec premier Jean Charest's decision to bow out of the Conservative leadership race is a turning point in a contest expected to heat up throughout the week as the party prepares for the return of the House of Commons.

Charest was a high-profile potential contender and his announcement Tuesday that he won't seek leadership of the party changes the playing field for those seeking to run and those mulling which candidate to support.

While some continue to wait to see if former interim party leader Rona Ambrose chooses to enter, others have already made up their minds.

Endorsements for Peter MacKay, who will launch his campaign at an event in his former riding of Central Nova on Saturday, have begun rolling in from current members of Parliament.

Charest had been reaching out to MPs and testing the waters for a leadership attempt since current leader Andrew Scheer announced his intention to resign last December.

But late last week, previously sealed police warrants were released, reviving allegations of illegal fundraising in the Quebec Liberal party during Charest's tenure as leader.

Charest has not been charged but his name surfaces in the documents. Through his lawyer, he has denied any knowledge of illegal donations.

His role with the Quebec Liberals, and his previous political life as leader of the federal Progressive Conservative party, had already seen some conservatives campaigning against him.

Among them, the National Citizens Coalition, a conservative lobby group, which sent out an essay warning against Charest's candidacy before he said he wouldn't run.

“Charest has the same kind of elitist sensibilities as Justin Trudeau, and is now completely out of touch with the base of the Conservative party,” it said.

Richard Decarie, a social conservative and longtime party organizer, had previously said that if Charest ran he would mount his own leadership campaign partially in a bid to stop him. Through a spokesman on Tuesday, he said he still intends to run.

Quebec movie-theatre mogul Vincent Guzzo had also been waiting to see what Charest decided to do as the two shared similar connections. On Tuesday, he said he is still thinking it over.

In his statement Tuesday, Charest said the party had changed a lot since his days in federal politics, and his decision not to run was based on that, as well as the tight timelines attached to the contest.

The deadline to meet the first set of requirements to register as a candidate - a payment of $25,000 and 1,000 signatures from Conservatives from 30 ridings across seven provinces and territories - is Feb. 27.

Another looming deadline is the return of the House of Commons on Monday, which will rein in the campaigns of some contenders.

At least three current Conservative MPs are expected to run. Marilyn Gladu, now in her second term representing the Ontario riding of Sarnia-Lambton, has declared she will enter. Pierre Poilievre and Erin O'Toole, both former cabinet ministers and current Ontario MPs, are also planning to run, though neither has explicitly announced.

O'Toole spent the weekend filming videos for his campaign launch, and was doing in meet-and-greets in the Toronto area Tuesday. Poilievre continues to make the rounds of party meetings to drum up support.

O'Toole, Poilievre and Gladu will no longer serve as critics in the House of Commons, and Scheer is likely to lay out other rules for how they'll need to balance their campaigns against the demands of the House.

Operating outside those restrictions is MacKay.

The former Conservative cabinet minister will begin to lay out his vision for the Conservative leadership later this week and then start a national tour.

Several current MPs have announced they support him, including some who backed O'Toole when he ran against Scheer in 2017.

Others are newer recruits. Ontario MP Ben Lobb, who endorsed Kellie Leitch in the 2017 race, said he's now throwing his support behind MacKay. He cited MacKay's experience and leadership, both within the party and externally.

Lobb said he's not concerned, however, that the race will see a breakdown of caucus unity as MPs line up behind rivals.

“At the end of the day, it's a desire to defeat Justin Trudeau that unites us,” he said.

This report by The Canadian Press was first published Jan. 21, 2020.