WINNIPEG -- Manitoba's transportation minister says resigning from cabinet before launching a leadership campaign to become the province's next premier was the honourable thing to do.

Steve Ashton says he met with Premier Greg Selinger to give him his resignation letter in person.

Ashton then announced his decision on Twitter, saying his official launch will come Tuesday.

As he packed up boxes in his legislature office, Ashton says the NDP needs to reconnect with voters after a tumultuous time.

He says the NDP can recover from disastrous polls following the provincial sales tax hike last year and go on to win the next election.

Ashton wouldn't say whether he would promise to roll back the tax hike but says he will put forward a platform that differentiates him from Selinger.

"We're in this critical situation, as a party and a government, but the fundamentals are good," Ashton said Monday.

"I believe we can actually reconnect, we can rebound and we can actually win the next election. I wouldn't be doing this if I didn't believe that was the case."

Ashton joins former cabinet colleague Theresa Oswald in challenging Selinger for the leadership. Selinger prompted the leadership race after coming under fire for the party's sagging fortunes following the provincial sales tax hike.

Ashton ran unsuccessfully against Selinger for the leadership in 2009 when then-premier Gary Doer resigned to become Canada's ambassador to the United States.

After running a campaign advocating the party return to its social justice and labour roots, Ashton garnered one-third of the vote.

His announcement, which was widely expected, comes after Oswald launched her leadership campaign over the weekend.

Party delegates will vote for a leader March 8.