Osmo Vänskä says he will resign as music director of the Minnesota Orchestra if the ensemble loses a prestigious engagement at New York's Carnegie Hall because of the current musician lockout.

In a letter to board chairman Jon Campbell and chief executive Michael Henson, Vänskä said he believes the orchestra needs to be playing by late May or, at the very latest, early September to achieve the proficiency needed for the Carnegie appearance — which he called one of the most significant goals of his tenure.

"I must make it clear, that in the case Carnegie Hall chooses to cancel the Minnesota Orchestra's concerts this November, i.e. if they lose confidence in our ability to perform … then I will be forced to resign," Vänskä wrote.

His departure would be a significant blow to the orchestra's prestige. Since arriving in 2003, he has catapulted a unit that was regarded as very good into a world-class ensemble, with two Grammy nominations and high-profile European tours.

Board chairman Campbell suggested in an interview Thursday that Vänskä should have directed his letter to the musicians instead of the board.

"They are the ones who are holding up the progress right now," he said. "We've responded to Osmo by saying he could help the process by encouraging the musicians to return to negotiations — to have real dialogue."

Last Friday the musicians' negotiating team told the board that they will not return to the bargaining table unless the lockout is lifted. In a statement Thursday, musicians said: "We hope management finally feels some urgency to end the lockout and get us back on stage."

Negotiations, which began 13 months ago, broke off when the contract expired Oct. 1 and musicians rejected a proposed 32 percent cut in annual minimum salaries. The musicians have not made a formal counterproposal. The two sides met once since, on Jan. 2.

Campbell said that when Vänskä signed a contract extension in 2009, he was given a heads-up that the business model was changing — in short, contract talks would be tough. Minnesota is one of many orchestras nationally that have been pinched financially.

"I'm disappointed because he agreed to the new business model and he's in a way not really able to stick with the plan we all had," Campbell said. "We've been pursuing a strategy to get serious negotiations going and I don't think there's anything in the letter that alters the plans we're working on."

The board has said it needs to cut $5 million in labor costs. The orchestra posted a deficit of $2.9 million in fiscal 2011 and $6 million in fiscal 2012. Previous years had balanced budgets only after the orchestra made extraordinary draws from its endowment.

Worried about departures

This is Vänskä's second plea to end the increasingly bitter dispute. In November, he addressed both sides, saying he was "desperately anxious" about the orchestra's future and urged them to "do what it takes ... and come to a resolution of this dreadful situation."

His latest letter, sent Tuesday, was more urgent and suggested the consequences of his departure and others'.

"The [orchestra's] musical policy of excellence ... is now under critical threat," he wrote. He said concertmaster Erin Keefe has been offered two positions elsewhere. "Although she does not wish to leave … she will be compelled to do so if the labor dispute remains unresolved."

In addition, Burt Hara, the orchestra's principal clarinetist, on Wednesday won an audition as associate principal in the Los Angeles Philharmonic.

"It is my duty to advise you that under these circumstances, my own position as Music Director may become unsustainable," Vänskä wrote.

He said he actually believes the orchestra needs to rehearse and perform the week of May 27, which would be the last week of the 2012-13 season.

He also expressed concern about a recording project scheduled with pianist Yevgeny Sudbin, beginning Sept. 16. "I consider it extremely important to make the recordings in September as planned — both in terms of maintaining our record-release schedule with BIS [his record label]; and as a part of the preparation process for Carnegie Hall."

Critical praise, financial woes

Vänskä, 60, is contracted through the 2014-15 season. His 2010 Carnegie engagement with the orchestra was a signal moment, as critics raved over a performance of Sibelius' epic work "Kullervo." New Yorker magazine critic Alex Ross said that on that evening, the Minnesota sounded to his ear like the best orchestra in the world.

However, Vänskä and the orchestra have not been able to leverage their artistic success into a sterling box office. "Kullervo," for example, drew only 52 percent capacity at Orchestra Hall before it went to New York. Ticket sales have declined in each of the past four seasons — though partly because the orchestra has reduced the number of concerts to keep expenses down.

Hara, who has been principal clarinetist for 25 years, said he would not have considered the Los Angeles job had the orchestra not been locked out. But he said he's looking forward to playing with celebrated conductor Gustavo Dudamel. "Times have changed and it's time to look to the next chapter," he said. "Dudamel is a hot commodity."

Graydon Royce • 612-673-7299