Bill Clark via Getty Images Complaints about Sen. Klobuchar's mistreatment of staff date back to her first run for Senate.

Minnesota Sen. Amy Klobuchar’s mistreatment of her office staff began more than a decade ago and eventually caused such concerns that in 2015, then-Senate Minority Leader Harry Reid (D-Nev.) spoke to her privately and told her to change her behavior, multiple sources have confirmed to HuffPost.

Klobuchar, a Democrat who plans to announce whether she’s running for president at a rally in Minneapolis on Sunday, has faced trouble hiring campaign aides because of her history of mistreating staff.

A spokesman for Reid said the retired senator prefers not to discuss private conversations he had with other senators. In this case, Reid also does not remember whether or not he had this discussion with Klobuchar, the spokesman said.

“Sen. Klobuchar is one of the most brilliant, hardest-working members of the Senate, and I was glad to serve alongside her,” said Reid. “She’s tireless when it comes to fighting for the people of Minnesota and the country, and that’s why she’s such a popular Senator back home and among her colleagues.”

But Reid’s 2015 admonishment of Klobuchar appears to have been a rare point of intervention in a long history of complaints about Klobuchar’s behavior, which date back to at least her time as the Hennepin County attorney in Minneapolis. That was the job Klobuchar had when she first ran for Senate in 2006.

During that first campaign, aides assembled an eight-page memo outlining the duties of Klobuchar’s body person, the staffer who oversees all of the logistics and personal needs of a candidate. It was frank about the challenges of working with the then-candidate.

“Especially while in the car during a busy day: if she is EXTREMELY upset about something, let her rant through it, DON’T interupt [sic] her unless ABSOLUTELY necessary and be careful when trying to calm her down,” the memo reads. “Often she just needs to talk things out in the open and is not interested in other people’s opinions―this is something that you will become used to and adjust to―its just a note for the first time this happens.”

In response, Ben Goldfarb, who managed her 2006 campaign, said, “Running for political office is incredibly hard for the candidate, their family and staff, and our team was proud to help elect her.“

[PREVIOUSLY: Sen. Amy Klobuchar’s Mistreatment Of Staff Scared Off Candidates To Manage Her Presidential Bid.]

During that same campaign, the president of the AFSCME local, the union that represented many of Klobuchar’s employees in the county attorney’s office, asked the larger Twin Cities AFSCME affiliate not to endorse Klobuchar’s Senate bid, citing her “shameful treatment of her employees.”

Klobuchar had “created a hostile work environment” and “severely damaged the morale of the office,” wrote James Appleby, the president of the local. The letter claimed that grievances to the union increased under Klobuchar’s tenure and that Klobuchar once told her own employees they weren’t competent enough to work at her former law firm. It also claimed the local had asked the union to withhold its endorsement for her county attorney bid in 2002.

“In short, Amy Klobuchar is exactly the kind of candidate that AFSCME should oppose,” he wrote.

The letter, which Appleby provided to HuffPost (and which is reprinted below), followed a contentious battle over potential pay raises for Klobuchar’s staff, more than 100 of whom were represented by AFSCME. The union claimed Hennepin County attorneys were among the worst paid in the state after years of being the best paid.

At the time, Klobuchar said she advocated for a salary increase but was constrained by budgetary concerns, and she disputed the letter’s claim that union grievances increased under her leadership.