Hirshhorn Museum and Sculpture Garden Director Richard Koshalek has resigned, effective at the end of this year, following an inconclusive vote by the Hirshhorn’s Board of Trustees on his vision for an inflatable architectural pavilion for the museum, according to a source who attended the meeting. (Update, 4:11 p.m.: Smithsonian spokeswoman Linda St. Thomas confirms to Arts Desk that Koshalek has resigned.)

The source, who spoke on condition of anonymity to discuss the private meeting, says Koshalek resigned because he didn’t believe he had support for his vision for the Hirshhorn—not just the so-called Bubble, designed by the New York architecture firm Diller Scofidio + Renfro, but also a project to transform the lobby into an education center and another project involving sculptor Richard Serra.

With Koshalek’s departure, plans for those projects will be canceled, the source says.

A spokeswoman for the Smithsonian, Linda St. Thomas, initially declined to comment, saying only that she has not seen a letter of resignation from Koshalek. The Hirshhorn’s communications department couldn’t immediately be reached for comment.

During a day-long meeting of the board, the trustees rendered an indecisive vote on the fate of the Bubble, with six trustees voting to recommend building it and six trustees voting against. The issue before the board today was a vote on whether to recommend it to the Smithsonian’s Board of Regents, not a vote on whether to build it.

An internal Smithsonian report commissioned by Richard Kurin, the Smithsonian’s undersecretary for history, art, and culture, had concluded that the Bubble would operate at a loss under each of the three scenarios officials examined, according to the Washington Post. The inflatable project was first proposed in 2009. Bloomberg LP had committed more than $1 million to the project, securing the right to name it the “Bloomberg Balloon” if it was actually built.

The Bubble’s final fate will be decided next month by Smithsonian Institution secretary G. Wayne Clough, in consultation with Kurin and others, according to Smithsonian officials. With a split vote, it is unclear what he’ll do. Clough couldn’t be reached immediately for comment.

While the Bubble vote was a factor in Koshalek’s decision, the source says, it was not the only one. Without the united support of the board or the support of the larger Smithsonian Institution, the source says, Koshalek would not be able to continue to pursue projects on the scale of Doug Aitken‘s SONG1 or the Barbara Kruger installation near the relocated museum store in the Hirshhorn’s basement.

The full text of a Smithsonian release on the Bubble vote:

The board of trustees of the Smithsonian’s Hirshhorn Museum and Sculpture Garden were unable to reach consensus on the fate of the Bubble. Some members of the board would like to proceed with the fundraising and others want to discontinue and focus on other museum priorities. Smithsonian Secretary Wayne Clough will consult with Richard Kurin, the Under Secretary for History, Art, and Culture and others, and will make an announcement in June.

Additional reporting by Ally Schweitzer and Jonathan L. Fischer

Bubble rendering courtesy Diller Scofidio + Renfro; Koshalek photo by Darrow Montgomery