WASHINGTON — President Obama sent Congress a plan on Tuesday to close the United States military prison at Guantánamo Bay, Cuba, his latest attempt to deliver on an unfulfilled promise of his presidency, which faces near-certain rejection by Congress.

The prison has come to symbolize the darker side of the nation’s antiterrorism efforts, but the series of steps that Mr. Obama outlined at the White House were as much an acknowledgment of the constraints binding him during his final year in office as they were a practical blueprint for transferring prisoners.

In presenting them, the president made little secret of his frustration that his quest to close Guantánamo, once regarded as a bipartisan moral imperative, had become a divisive political issue.

“I am very cleareyed about the hurdles to finally closing Guantánamo: The politics of this are tough,” Mr. Obama said during a 17-minute address. “I don’t want to pass this problem on to the next president, whoever it is. And if, as a nation, we don’t deal with this now, when will we deal with it?”