Senator John Hoeven, a North Dakota Republican who is a chief sponsor of the bill, said, “You’ve got Congress approving it on a bipartisan basis. All six states on the route have approved it. The Nebraska court decision is done. The American people overwhelmingly support it. The president has to consider all that when he makes his decision.”

On that point, environmentalist opponents of the pipeline agreed. “This issue is ready for a decision,” said Michael Brune, execuive director of the Sierra Club, one of the groups that has held hundreds of rallies outside the White House and around the country, urging Mr. Obama to reject the project. “After the agencies have weighed in, this issue has been examined enough and the president has everything he needs to make this decision.”

After all this time and deliberation, Mr. Brune also expressed confidence that Mr. Obama would reject the pipeline.

“I bet your lunch he’ll reject it,” he said. “We’re very confident he’ll say no.”