Becky Barrett, a former minister who currently sits on the provincial NDP executive as vice-president for the Interlake region, told Winnipeg radio station CJOB Selinger must think hard about staying on given public anger over last year's sales tax increase.
"There are a number of people who have shared their concerns — and continue to do so — and I think it's critical that he make a decision and do so very quickly," she said.
Media reports, based on anonymous sources, of internal dissent within the party have been growing in recent weeks. Barrett's radio interview Monday was the first time a well-known party member went on the record.
The NDP plummeted in opinion polls after raising the provincial sales tax last year to eight per cent from seven. Selinger had called the idea of an increase "ridiculous" in the 2011 election campaign, but later said he had to change his position to help the economy and fund much-needed infrastructure work.
In a followup interview, Barrett said it's clear some Manitobans have lost trust in the premier. Selinger has to decide whether he will run again and, if so, outline a game plan to win the next election slated for April 2016, she suggested.
"I think the basic concern is that the premier has not addressed the feeling that the majority, it appears, of Manitobans have that he lied to them and he betrayed their trust," said Barrett, who served in cabinet from 1999 to 2003.
"If he's running again, he has to ... begin rebuilding that trust and every day that he doesn't do that is a day that makes it more difficult for him and the party in the next election."
Selinger was not available for comment Monday. His communications team issued a written statement saying he "remains focused on the job he was elected to do — delivering on the priorities of Manitoba families, creating jobs and opportunities for young people, and growing our economy."
Stan Struthers, minister responsible for municipal government, also said Selinger must consider his future given recent poll numbers.
"I think that the premier will be very diligent about this and he will take a look at all of the figures in front of him and he needs to reflect on those."
Finance Minister Jennifer Howard would only say that politicians always need to assess their futures.
"When you hear senior party members express the concerns that have been expressed, you have to pay attention to that," she said, referring to Barrett's remarks.
A few backbench members approached by The Canadian Press refused to weigh in on whether they want Selinger to leave or stay. Dave Gaudreau, who won the St. Norbert seat by a razor-thin margin in 2011, said he was focused on "all the construction in my area and getting even more projects done. The millions in investments that I have been able to have invested for my constituents are my priority."
Selinger did garner firm support in some quarters. Family Services Minister Kerri Irvin-Ross said she backs Selinger "100 per cent" and added that raising the sales tax has paid off.
"We can see the results of that decision now with better roads, with better flood protection and knowing that Manitobans have access to good-quality health care, education and social services."
Rosann Wowchuk, a former finance minister who now co-chairs the premier's election planning committee, also backed Selinger.
"There are some people that are unhappy, but there are a lot of people who are also very happy with what is going on," Wowchuk said.
"It's just like within a family, where you may have disagreements. But you have to sit down, you have to work through those disagreements, find solutions and continue to move forward."
The NDP has been in power since 1999. The party captured 37 of the 57 legislature seats in 2011 while taking 46 per cent of the popular vote.
Recent opinion polls suggest that support is now in the low-30s and well behind the Opposition Progressive Conservatives. The most recent sign of trouble came in last week's mayoral election in Winnipeg, where longtime New Democrat Judy Wasylycia-Leis finished a distant second to winner Brian Bowman.
One political observer predicted that while people are now openly discussing Selinger's future, the premier is likely to survive unless there is an open revolt by members of his caucus.
"When caucus members start openly opposing the premier, then it becomes a whole different game," said Royce Koop, who teaches political science at the University of Manitoba.
"I just can't see this shadow campaign unseating a sitting premier."