Prime Minister Paul Martin sent a clear signal that he'll call an election for June when he thanked his caucus and all MPs for their service Wednesday.

Martin will be out of the House on Thursday and Friday and the Commons doesn't sit next week, making June 28 a virtual certainty for a federal election.

Martin bid his adieus at a closed door caucus meeting earlier Wednesday, then delivered a similar message to all MPs in the Commons.

"A number of members have risen in this House to thank their colleagues on both sides of the House who've contributed so much," Martin said at the start of Question Period.

"Perhaps they will allow me on behalf of all Canadians to thank those who have served with such distinction."

That triggered a standing ovation in the chamber, with MPs from both sides of the House rising to applaud colleagues who will be departing.

Sources say Martin didn't mention a date in the caucus meeting, but thanked senators and MPs for all they've done during their mandate.

There is speculation the prime minister will go to the Governor General on Sunday, May 23 and set the election date for June 28.

MPs who won't run again also began thanking their constituents from the floor of the Commons.

An emotional John Manley, the former finance minister, thanked Ottawa voters for their support.

May 23 would be the latest date to call a June 28 election, to meet the rule of a 36-day minimum campaign.

Martin the key

"The Liberal hierarchy held a war council last night, and decided -- with the agreement, for the first time, of Ontario and Quebec -- to go for it," said Craig Oliver, CTV's Ottawa bureau chief.

The Liberals will be seeking their fourth majority government since being first returned to power in 1993.

"This is going to be a high-anxiety campaign for the Liberals," Oliver said.

They have no over-riding issue or momentum, but they feel Martin is their best weapon, he said.

"They think if there is a defining issue, it will be a psychological, subterranean one. And it will be trust, believability -- and that Martin has the history to prove he has those things, and neither of the other two leaders does."

Besides that, the Liberals have been making all types of spending announcements, he said.

One surprise that came out of the caucus meeting was Martin mentioning his predecessor Jean Chretien by name, Oliver said.

The two men have been bitter rivals going back to when Chretien defeated Martin for the Liberal Party's leadership in 1990.

Since Martin took the helm in December, the sponsorship scandal exploded, there were bitter nomination meetings, and Chretien loyalists accused Martin operatives of trying to conduct a purge.

"Martin told a cheering caucus this morning that they will run on the Chretien record. And surprise, surprise, the Chretien record gave the Liberal Party more popularity than it has now," Oliver said.

However, some of those Chretien-era MPs termed Martin's conciliatory remarks as being too little, too late.