Campbell said while the operating budget for the current fiscal year remains in the black, he and Premier Jim Prentice are promising "tough decisions" so that Alberta is no longer captive to the whims of the international marketplace.
"We have to get to a position where we're not listening to OPEC to decide on how many schools we're going to build," Campbell told reporters as he delivered the second-quarter budget update.
"If oil stays at $75 (a barrel) next year, we're going make some tough decisions.
"One of the things the premier has tasked me with is that we have to get off the oil (price) train."
Campbell said he has not looked into changing taxes right now but is focused on balancing the budget for this year.
In the March budget, the province forecast West Texas Intermediate oil to average around US$92 a barrel.
For the first six months of the year, it was higher than that, around $100 a barrel.
But higher production in the U.S., coupled with instability in other oil producing regions, has sent the price plunging to $75 with no end in sight.
Campbell said the province will now assume that price won't rise for the rest of the fiscal year, bringing the revised forecast average to almost US$89.
The budget forecast an overall budget surplus of $1.1 billion this year. That is now down to $933 million, said Campbell.
The province says it's also on track to bring its debt total for infrastructure to $11.2 billion. Opposition critics have said when you take that debt into account, the budget is not balanced, but deeply in the red.
Alberta has chronically struggled with oil prices wreaking havoc on its budgets, delivering billion-dollar windfalls and shortfalls on short notice.
Speculation has been growing in recent weeks that Prentice is planning to hike income and corporate taxes or reform Alberta's 10 per cent flat tax to reduce that dependence.
Prentice has declined to offer specifics except to say there will be no sales tax and that overall taxes will remain low.
While Prentice has warned that $75 oil "does not mean business as usual," NDP finance critic Brian Mason said Wednesday that is exactly what it means.
He warned that workaday and disadvantaged Albertans will pay for the Tories' budgeting follies.
"In Alberta when the price of oil goes down and they start cutting health care and education, that is pretty much business as usual," said Mason.
Mason said the Tories need to toss out the 10 per cent flat tax, which he says places an unfair burden on middle and lower-income earners, and reinstitute recent cuts to corporate taxes.
Wildrose finance critic Rob Anderson said hiking taxes is not the answer.
He said the Tories have been running deficits even with oil at record prices and needs to trim the fat in the civil service and elsewhere before asking Albertans for more money.
"It's a revenue problem because of the spending problems of the last, frankly, decade," said Anderson.
"Our entire budget is out of whack. It needs to be recalibrated to $80 a barrel oil."
Liberal finance critic Kent Hehr agreed that the problem is not the mercurial price of oil, but how the Tories have failed year after year to adapt to it.
"This crisis hasn't just come about as a result of $80 or $75 oil. This crisis was here at $100 oil," said Hehr.
He noted that even when oil prices were high in recent years, the Tories failed to build the promised schools for children and long-term care spaces for seniors.
In the second-quarter update, Campbell said the total revenue forecast is now $45 billion, $637 million more than estimated at budget.
Total expenses are now pegged at $44.1 billion, up $791 million from budget due to increases in infrastructure spending and disaster aid.