Outgoing Alberta Premier Alison Redford saw her approval rating plunge to 18 per cent, the lowest of all the party leaders in the province, before announcing her resignation as leader of the Progressive Conservatives.

The latest poll released by Calgary public relations firm ThinkHQ on Wednesday shows Redford鈥檚 approval rating dropped 40 points over the last year and a half.

"There's not a lot left in terms of room to fall," Marc Henry of ThinkHQ told CTV's Power Play on Wednesday.

The premier's approval rating dropped even further after announcing she had paid back about $45,000 for a trip to South Africa for Nelson Mandela鈥檚 funeral. Before she agreed to pay back the money, Redford鈥檚 approval rating was 19 per cent.

Following weeks of controversy, Redford announced on Wednesday evening that she would resign her post as premier. She is expected to step down Sunday.

The ThinkHQ poll shows Redford鈥檚 popularity has been on a steep decline since the expense scandal surfaced. In August of 2012, her approval rating was at 58 per cent. In January 2014 it had fallen to 35 per cent, before dropping to 18 per cent in March 2014.

Henry said the last sitting Alberta leader to see approval ratings under 20 per cent was Don Getty, who was premier from 1985 to 1992.

But Henry pointed out that the Alberta economy was "grim" at the time.

"Today in Alberta, the economy is humming along quite nicely, and yet we have a sitting premier with a majority who is in sub-20 per cent in the polls," he said.

In the wake of Redford's travel controversy, the poll showed:

  • 55 per cent of Albertans polled believe Redford showed bad character
  • 33 per cent said she showed bad judgement
  • Eight per cent said she really didn't do anything wrong
  • Four per cent were unsure

Redford's plunging popularity has also had a serious impact on the PCs.

Of those 1,688 individuals polled, 25 per cent said the travel controversy wouldn't influence their vote, while 70 per cent said they are less likely to vote PC and two per cent said they're more likely to vote for the party.

The PCs took 44 per cent of the popular vote in the last provincial election, but if an election were held tomorrow the latest survey shows:

  • 46 per cent would vote for the Wildrose Party
  • 19 per cent would vote for the PCs
  • 16 per cent would vote Liberal
  • 15 per cent would vote NDP

Meanwhile, Wildrose leader Danielle Smith approval rating is the strongest amongst the provincial party leaders at 51 per cent, followed by NDP Leader Brian Mason at 37 per cent and Liberal Leader Raj Sherman at 36 per cent.

However, Henry said the Tories have "an incredible talent" for staying in government, adding that the PC brand in Alberta is "probably the most resilient political brand in Canada."

"They also tend to know when their premier, their leaders, have worn out their welcome," he added.