KNOXVILLE, Tenn. — President Obama introduced his plan Friday for free community college, one of his most ambitious, expensive and likely controversial initiatives for the coming year.

“Today I'm announcing an ambitious new plan to bring down the cost of community college tuition in America,” Obama said in a speech at Pellissippi State Community College here. “I want to bring it down to zero. I want to make it free."

The White House estimated that the cost of the program would be "roughly $60 billion over 10 years” and would, if all states choose to participate, include about 9 million students, said an administration official.

The president didn’t delve into the details of his program, but rather made a broader case that attending community college shouldn't be any more expensive than high school is today. “America thrived in the 20th century in large part because we made high school the norm,” he said. “Eventually the world caught on and the world caught up and that’s why we have to lead the world in education again.”

Under the White House’s plan, the offer of free tuition would extend to all students if they attend classes at least half time and maintain a grade point average of 2.5 or better. The federal government would cover up to 75 percent of the costs of the initiative, while states would pick up the remaining quarter.

Obama’s plan would be among the biggest federal programs ever proposed for community colleges. Despite the grand ambitions and vast scope of Friday’s proposal, there are still big unanswered questions about how many states and students will take advantage of it. Perhaps the biggest question was whether the potentially costly initiative will garner enough bipartisan support to get through a Republican-controlled Congress. The White House plans to include money for it in the coming budget.

The president chose Tennessee to introduce his plan largely because the White House community college plan is modeled on an effort by the state’s Republican governor as well as a similar program launched in Chicago. Still, even some Tennessee Republicans expressed doubts about the new community college effort.

Sen. Bob Corker (R-Tenn.) who traveled to attend the speech from Washington with Obama, praised Tennessee’s free community college tuition program, but he said a big federal program wasn’t needed to extend community college to more students. Instead he said he preferred more tailored state and local efforts.

“You're always better off letting states mimic each other,” he said.

House Speaker John A. Boehner (R-Ohio) criticized the White House for not providing a more detailed blueprint. “With no details or information on the cost, this seems more like a talking plan than a plan,” he said.

The White House is betting that public support for the free tuition plan will pull along Republicans who are skeptical about the cost or reluctant to back an Obama administration initiative. The White House said that more than 5.7 million people viewed a Facebook post Thursday of the president describing the plan.

Obama is clearly counting on bipartisan support for the community college effort and repeatedly reached out to Republicans in his speech for backing. “Opening the doors of higher education shouldn't be a Democratic issue or a Republican issue,” Obama said. “This is an American issue. If a state with Republican leadership is doing this and a city with Democratic leadership is doing it, then how about we all do it.”

Similarly, White House officials has billed the president’s address as the beginning of a conversation about higher education in the U.S. with the goal of making two years of college the norm for all Americans, just as high school is today.

The Tennessee program is estimated to have cost $14 million in its first year and provides tuition assistance for students at 13 of the state’s community colleges. Tennessee officials expect as many as 16,000 students to take part in the program.

Obama has said that his upcoming State of the Union address will focus on making sure that middle class families will benefit from the improving economy with increased wages and home values, both of which have lagged during the current recovery.

“A college degree is the surest ticket to the middle class,” Obama said Friday. “It ensures you are always employable.”