"This announcement this morning was nothing more than an attempt to curry favour before they (the Tories) drop the writ," Wildrose critic Shayne Saskiw told a legislature news conference Friday.
"The PCs have played this game for years, and it's time for that to end."
NDP Leader Rachel Notley said using public money to campaign on is a common tactic for the Tories, but added that funding is critical to municipalities.
She said the announcement was also to deflect attention from controversial comments made this week by Premier Jim Prentice.
Prentice, on a radio call-in show, told Albertans to "look in the mirror" if they want to understand who is at fault for the projected $7-billion hole in next year's budget.
Prentice has said the remark was misinterpreted, but Notley said his government is still trying to do damage control.
"(It's) trying to change the channel from an embarrassing political situation that the premier has got himself into," said Notley.
The $400 million in infrastructure money, highlighted last week in the government's third-quarter budget update, was re-announced by Municipal Affairs Minister Diana McQueen.
McQueen told reporters that it's important to continue to build, even though slumping oil prices mean tough times ahead for Alberta's economy.
"Municipalities have a number of key infrastructure project commitments that will require provincial investment," said McQueen.
"Forgoing these key projects could mean that they could cost more later and we may miss an opportunity to take advantage of lower construction costs."
The new infrastructure money brings to $1.6 billion the total amount of cash invested in the Municipal Sustainability Initiative this year. The money has been used to support close to 5,000 infrastructure projects, including rapid transit and road repair.
Finance Minister Robin Campbell has already said the March 26 budget will have an impact on everyone and will include five per cent spending cuts across the board.
At the same time, Campbell will introduce a 10-year plan to overhaul how Alberta raises and spends money to cushion day-to-day financing from the shock of wild swings in oil prices.
Prentice has said the blueprint will be so revolutionary that any leader who wishes to implement it will need a mandate from Albertans.
All parties are busy signing up candidates for an election call expected to come as early as the end of March.