It isn’t clear who the next leader of the Machinists union in metro Puget Sound will be, and union officials expect a contested election sometime this spring.

Several rank-and-file leaders are backing a union staffer based in Everett, Jon Holden, to succeed Tom Wroblewski, the current president of Seattle-based District Lodge 751. About 33,000 Boeing workers are members of that district of the International Association of Machinists and Aerospace Workers (IAM).

Earlier this month, Wroblewski unexpectedly announced that he would resign at the end of January.

An interim district business representative will run day-to-day operations until an election is held this spring.

Holden “is the right man to bring the membership home and restore their faith in the leadership, and repair our solidarity,” said Wilson “Fergie” Ferguson, a rank-and-file leader backing Holden.

Ferguson is a mechanic on the Boeing 737 flight line in Renton, the district’s vice president and president of Local A.

Ferguson’s charismatic personality and candid criticism of union leadership during recent contract negotiations boosted his popularity with many members. After Wroblewski said he would step down, several members called on him to run.

But Ferguson said Holden has the experience needed to reform the district.

Holden spent about six years working at Boeing before spending about three years as a union organizer and the past 11 years as a business representative, an elected position, according to Ferguson.

The two “have committed to work to restore the membership to power,” he said.

The recent contract negotiations proved that the district has to be stronger and more inclusive, he said. “For too long, we haven’t heeded (all members’) voices, and we have become complacent.”

Asked for an example, he pointed to the district’s decision to save money by using staff members rather than volunteers during an organizing campaign a few years ago.

So business representatives were out trying to organize employees at non-union companies.

“The end result was that the reps weren’t around when our members needed them,” he said.

Organizing is important, but the union has to take care of present members first, Ferguson said.

The union also needs better contract enforcement, he said.

Holden hasn’t officially announced his candidacy and could not be reached for comment late Thursday. He will have to leave his staff job and return to the shop floor. To run for district president, he has to be on the district council.

Wroblewski’s council seat will be vacant come Feb. 1, so Holden will have to petition to be appointed to finish Wroblewski’s term on the council before he can run for president.

Even if he is appointed to the council, Holden is likely to face challengers. Two other district council members are reportedly considering running, and the recent contract negotiations left the membership deeply divided.

The next president needs “to mend fences between the vote yes and the vote no sides,” said Lester Mullen, a rank-and-file activist.

“We need people that have differing views to be there so we represent the diverse needs of our members,” he said.

The process for picking the next district president isn’t clear, though.

District officials have asked the IAM’s international headquarters in Upper Marlboro, Md., to approve holding nominating meetings at the end of February*, with an election following a few weeks after. The international hasn’t responded yet, said Connie Kelliher, a spokeswoman for District 751.

The international did not respond to requests for comment.

The District 751 Council is expected to formally set the dates for nominating meetings and the election on Tuesday, and the details will be in February’s Aeromechanic, the district’s newspaper, and on its website, Kelliher said.

Correction, Jan. 24, 2014: This article has been updated to note that District 751 asked to hold nominating meetings in February, not in March as originally reported.