WASHINGTON — The White House is working on early drafts of a comprehensive bill that would offer 11 million illegal immigrants a pathway to citizenship along the lines of the principles that the president laid out in Las Vegas several weeks ago, administration officials said.

President Obama revealed last month that his administration had already drafted immigration legislation. But he said he preferred to let a bipartisan coalition of lawmakers work out their own bill that could also tighten border security and provide employers with a way to verify the citizenship status of workers.

White House aides said that Mr. Obama remained pleased with the progress being made on Capitol Hill toward a complete overhaul of the nation’s immigration system. But they said he would be prepared to submit legislation if the effort among lawmakers stalls.

“The president has made clear the principles upon which he believes any common-sense immigration reform effort should be based,” Clark Stevens, a White House spokesman, said in a statement. “We continue to work in support of a bipartisan effort, and while the president has made clear he will move forward if Congress fails to act, progress continues to be made and the administration has not prepared a final bill to submit.”