Brian Jean represented Fort McMurray-Athabasca in the House of Commons between 2006 and 2014 and the Athabasca riding from 2004 to 2006.
He describes Alberta Premier Jim Prentice, his former caucus colleague, as a "nice guy," but says the two men have different values.
"I have nothing bad to say about Jim Prentice except that I think he's getting it wrong," Jean said Wednesday at a news conference to announce his intentions. "I think he's headed the wrong direction."
Jean, 52, said he wants to clean up an under-performing health-care system in Alberta and deal with fiscal mismanagement by the governing Progressive Conservatives.
The lawyer said he also wants to lift up the Wildrose, which was blindsided last December when leader Danielle Smith and eight caucus members crossed the floor to join the government.
Jean said he views the move by the former official Opposition members as a betrayal and believes many Albertans share his opinion.
But he also recognizes that the party's chances of recovering sufficiently to win the next provincial election are slim.
"Bluntly I don't think it's one that we can win at this stage. It is a rebuilding one," Jean said.
"We need a solid opposition that can keep this government to account — and that's what we're going to do," he said. "We're going to make sure we reach all parts of Alberta, bring together good candidates and we will build a strong opposition."
Derek Fildebrandt, a former spokesman for the Canadian Taxpayers Federation, is supporting Jean. Fildebrandt has been acclaimed as the Wildrose candidate in the Strathmore-Brooks constituency, but had indicated he might run for the leadership.
"I told members that I would consider my future and that I would do the right thing for the Wildrose and for Alberta. And ... the right thing is standing here today and supporting Brian Jean," Fildebrandt said.
Jean served as parliamentary secretary to the minister of transport, infrastructure and communities and was on the finance, justice and industry committees before resigning a year ago.
After he left politics, he said that oilsands development should be slowed to ensure a better quality of life in Fort McMurray. He pointed to the region's need for expanded highways, more hospitals and additional seniors services
He hasn't changed his opinion.
"I invite you all to come up to Fort McMurray and see what happens when oil production is not managed properly, when there's no foresight, when there's no vision," he said Wednesday.
With speculation that Prentice might call an election this spring, the Wildrose has changed its mind about having a leadership vote June 6 and has moved that up to late March.
Other candidates include current Wildrose member Drew Barnes and former Strathcona County mayor Linda Osinchuk.
Follow @BillGraveland on TwitterSuggest a correction