Days after a marathon endorsing convention ended in a deadlock, state Rep. Phyllis Kahn and her two challengers are preparing for a three-way primary that is expected to be one of the most expensive and bruising DFL elections of the year.

The Minneapolis race is opening rifts within the Somali-American community, as well as between young and old residents and white women and women of color.

Former Mayor R.T. Rybak announced Tuesday that he is endorsing political activist Ilhan Omar, after he had backed the third candidate in the race, Mohamud Noor, in his run against Kahn in 2014.

It was the latest statement of support, along with that of DFL Sen. Scott Dibble, in a growing list of endorsements that Omar has gathered in her bid to unseat an incumbent first elected in 1972.

The race already has drawn enormous attention from DFLers who are eager to elect the first Somali-American to the Minnesota Legislature, joining fewer than a dozen legislators of color at the Capitol.

Rybak said Omar reached out and made her case to him months ago. He said he chose to back her after it became clear that she had the most support at the party convention Saturday. Omar led her opponents with 55 percent of the delegate vote after five ballots, but fell short of the 60 percent she needed to win the DFL endorsement.

The former mayor said he called Noor the night of the convention to tell him that he would support Omar “because I thought that she had the best chance of winning … this time, the best opportunity for a new voice to come forward is her.”

Noor gathered about 11 percent of the vote and was forced to drop out after the second ballot due to the lack of support. If his delegates had sided with Omar, she would have won, but they voted on subsequent ballots for no endorsement. Noor said it became part of his political strategy to go to a primary, which has a broader voter base than the narrow slice of activists at the endorsing convention. But tensions have simmered between him and Omar, who worked for Noor during his contentious race against Kahn in 2014.

On Tuesday, Omar called Noor’s move “unfortunate,” noting that a large part of the district would not be able to participate in the August primary. She was referring to college students, who have been among her most vocal supporters.

She said it was clear from ballot results at the convention that two-thirds of the delegation did not want to stay with the incumbent. “My hope was that Noor would see the writing on the wall” that people wanted new representation, she said. “It was sad for all of us in that room Saturday to see him make it about himself and not about the goodwill of the people of the district.”

While Noor said he was clear about his intent to run again after his loss in 2014, Omar said he did not announce his latest campaign until after she did.

“We were all in dismay about that,” she said. “I don’t think any of us have a clear understanding” of why he’s running.

Noor said that he did not believe in investing a lot of resources in trying to win an endorsement in a three-way race. He said he only wanted to send a message that he was in the running.

“That was the strategy … that worked for us,” Noor said. “It wasn’t going to be easy for us, no matter how many delegates I brought.”

Kahn drew blowback from Omar’s campaign by publicly describing the candidate as younger, prettier and more agreeable than she is. Omar’s campaign called the remarks “offensive” and “derogatory,” especially from a longtime feminist.

“I said that she’s younger and prettier,” Kahn said Tuesday. “Both of those are true statements. I don’t consider them negative statements. … I’d love to be younger and prettier.” She described part of Omar’s appeal as being nicer and having a more appeasing personality.

Kahn also questioned why Omar is running against her when they have no real policy differences. All three candidates say they support raising the minimum wage to $15 an hour, instituting paid sick leave, expanding educational opportunities and addressing disparities in opportunity between whites and people of color. And Kahn questioned the depth of Omar’s legislative experience. Although Omar has done some advocacy work at the Capitol, Kahn said Omar has less experience advocating at the Legislature then she did when she ran in the early 1970s.

But more Democrats are joining Omar’s cause.

“Minnesota needs Ilhan Omar’s voice in the Legislature and I am very proud to step forward and endorse her,” Dibble, a DFLer from Minneapolis, said in a statement Tuesday. “I’ve seen Ilhan in action and know that she is a coalition builder and will move social, racial, economic and environmental justice issues forward at the Capitol.”

Rybak said that there’s a lot to say for experience in public office, but “these positions aren’t lifetime appointments and it’s good to have some fresh energy.”

He did not publicly criticize Kahn in endorsing Omar.

“That doesn’t say somebody is doing a bad job, it’s just saying we benefit by every once in a while, or in this case every few decades, from having a new voice,” he said.