Many of Bernie Sanders’ Oregon delegates to the national convention have complained they are being treated unfairly by the state party, and they said they want tighter control over the delegation.

Bernie Sanders handily defeated Hillary Clinton in Oregon's May primary. But many of his supporters believe party regulars ran over them after delegates were chosen a month later.

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Sanders delegates said Thursday that at least 19 of them will file an official challenge to the way state party officials ran a meeting that selected the leadership of the delegation to the Democratic convention in Philadelphia.

Sanders supporters have raised complaints in a number of states, saying the party establishment is biased against them and has been showing unfair favoritism toward Hillary Clinton, the party's presumptive nominee. The complaints from grassroots Sanders delegates indicate they aren't ready to quietly attend the Philadelphia convention and cheer Clinton on when she becomes the party's nominee.

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Three Sanders delegates from Oregon — Abby Collins of Portland, Jeremy Likens of Cornelius and Lisa Ortiz of Lake Oswego — said in a joint interview with OPB that they believe a Sanders supporter should lead the delegation in Philadelphia.

Instead, Sen. Jeff Merkley was chosen to co-chair the delegation with Sen. Ron Wyden. Merkley endorsed Sanders, while Wyden backs Clinton.

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Likens said the chairmanship role is often ceremonial, but that might not be the case in Philadelphia when Sanders delegates will be pushing to change the party platform.

"So, it actually matters who is the delegation chair," he said. "We want to get our issues heard and make sure we're well-represented."

Likens added: “The point is we are just not going to lay down when things are done improperly.”

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The three Sanders delegates said the party has 10 days to respond to their challenge, which they will file Friday. If the state party won't agree to a new election for delegation chair, they said they will take it to the credentials committee that will meet in advance of the convention.

Party leaders did not immediately comment on the complaint.

However, several party leaders have privately dismissed the complaints, saying they didn't see any problems in the way the chairman selection meeting was run. They have also noted that Merkley wanted to co-chair the delegation with Wyden, and that a majority of the delegates voted in favor of that arrangement.

However, Likens, Collins and Ortiz counter that many Sanders delegates were new to the process and weren't given time to plot strategy.

All told, Sanders has 36 pledged delegates from Oregon, while Clinton has 25. Another 13 elected and party leaders are superdelegates who can vote however they want.

The Sanders delegates said Merkley held a conference call with them Wednesday evening to discuss their complaints.