Seattle Seahawks quarterback Russell Wilson and singer Ciara have joined the effort to bring Major League Baseball to Portland.

Portland Diamond Project, the company leading the push, announced Friday morning that the husband-and-wife celebrities have each invested individually as "owner/investors" in the project. In doing so, they become the first outside investors to publicly announce their support.

"I want to see this vision come to life and empower more women owners in major sports franchises," Ciara said in a news release.

Each has pledged to hold a minority ownership stake should Portland acquire an MLB franchise, spokesman John McIsaac said.

"We believe Portland is the next great Major League Baseball city, and that's why Ciara and I are excited to announce we are a part of the Portland Diamond Project," Wilson said in a news release. "It is time for MLB in Portland."

The Diamond Project's leadership has stressed that its effort will take time, estimating an opening day in Portland would come in 2022 at the earliest. MLB commissioner Rob Manfred has called Portland a candidate to acquire a franchise whether by either expansion, which hasn't happened in 20 years, or relocation. The Oakland Athletics and Tampa Bay Rays are the likeliest candidates to move because each has pushed for a new stadium with little headway to show for it.

"I want to be clear about expansion," Manfred said in a May 30 interview with The Athletic's Ken Rosenthal. "We're fortunate. I would not have raised the issue of expansion. We've made clear we have two big issues -- Tampa Bay and Oakland -- that need to be resolved before we think about it. But the fact of the matter is, we're blessed. We've got cities out there that want to have Major League Baseball. And I think Major League Baseball has to show some receptivity to that because down the road, we are interested in it."

Friday's announcement is the latest in the effort to bring baseball to the country's 22nd-largest media market. Retired Nike executive Craig Cheek, former state senator Jason Atkinson and former Trail Blazers announcer Mike Barrett are Portland Diamond Project's managing partners.

In April, the group placed offers on two sites on which it hopes to one day build a 32,000-seat stadium and 8,000 units of housing. One offer is for the ESCO industrial site in Northwest Portland that used to be the home of Vaughn Street Stadium, a longtime baseball venue in the city. The other is an $80 million offer for the Portland Public Schools administration building near Moda Center and Memorial Coliseum.

Wilson and Ciara will tour the ESCO and PPS sites Saturday before speaking at a news conference.

A third site -- the Port of Portland's Terminal Two, on the Willamette River's west bank northwest of the Fremont Bridge -- is also being considered, the Port confirmed Thursday in news reports.

Key state and city local officials offered a tepid welcome in April when the Portland Diamond Project's offers to buy land were made public. At the time, Portland Mayor Ted Wheeler said city resources would be best directed toward priorities such as housing and public safety. But in a series of tweets Friday morning, Wheeler praised the baseball group.

"Watching the @PDXDiamondProj steadily gain momentum over the past few months has been exciting, especially in light of today's announcement that @DangeRussWilson and @Ciara have signed on as investors," Wheeler wrote. "Bringing a @MLB team to Portland could have many extremely positive economic and social ramifications for the city, and I look forward to looking hearing more about the possibilities of this initiative."

Watching the @PDXDiamondProj steadily gain momentum over the past few months has been exciting, especially in light of today’s announcement that @DangeRussWilson and @Ciara have signed on as investors. (1/2) https://t.co/PxoWJqhLzl — Mayor Ted Wheeler (@tedwheeler) June 1, 2018

Bringing a @MLB team to Portland could have many extremely positive economic and social ramifications for the city, and I look forward to looking hearing more about the possibilities of this initiative. -TW (2/2) — Mayor Ted Wheeler (@tedwheeler) June 1, 2018

In a blog post, Wilson wrote Friday he hopes the project will help inner-city youth find a connection to baseball as he did as a child, recalling how his parents took him to games.

"With this project, we will make sure that every little kid in this country has the opportunity to learn the lessons of sportsmanship and competition," Wilson wrote. "No matter their skin color or economic status every kid deserves to have an equal opportunity and the resources it takes to play."

Cheek said the relationship with Wilson and Ciara began while he oversaw the NFL for the global sportswear giant based in Washington County.

Though Wilson is a Pro Bowl quarterback, he has a longstanding connection to baseball. He played in the minor leagues while in college and practiced with the Texas Rangers during spring training in March. He has also lent his status and invested his money in previous franchise-acquisition efforts. In 2016, Wilson joined a push to build a Seattle stadium that could hold NBA and NHL franchises.

-- Andrew Greif

agreif@oregonian.com

@andrewgreif