In a State of the Union address defined by its economic and foreign policy rhetoric, President Barack Obama said Tuesday night that states should require all students stay in school until they either graduate or turn 18.

"We... know that when students aren’t allowed to walk away from their education, more of them walk the stage to get their diploma," Obama said in his address to the nation and Congress.

In a document further explaining Obama's proposals in the State of the Union, the administration said that 20 states already have such a requirement in place. The White House also cited unspecified studies that have found "stronger dropout laws keep students in school longer and increase their lifetime earnings as a result."

Jon Kuhl, spokesman for the National Conference of State Legislatures (NCSL), told Governing that, because the federal government contributes about 10 percent of education funding to states and school districts, there are cost concerns for state and local entities in implementing Obama's proposal. "With this in mind, if the federal government wants to mandate a change, they're going to have to pay for it," Kuhl said.

Obama's plan would also ask the U.S. Department of Education to establish a new competitive grant program in which states and school districts would be asked to collaborate with teachers unions "to comprehensively reform the teaching profession." The plan was not directly addressed by Obama in his formal remarks, although he did emphasize the need for a stronger teaching workforce.

"A great teacher can offer an escape from poverty to the child who dreams beyond his circumstance. Every person in this chamber can point to a teacher who changed the trajectory of their lives," Obama said. "Most teachers work tirelessly, with modest pay, sometimes digging into their own pocket for school supplies -- just to make a difference."

The grant program would be based on a number of reforms, according to the White House's proposal: making colleges of education more selective; ensuring that pay is tied to performance; improving professional development and exchanging autonomy for accountability; basing evaluation systems on metrics beyond test scores; and reforming tenure.

“We appreciate the president’s call to support teachers and to stop teaching to the test,” National Education Association President Dennis Van Roekel said in a statement after the speech. “Teachers and educators are eager to work with the Obama administration on ideas to strengthen the profession of teaching and help all students succeed.”

Obama also introduced recommendations for improving higher education, saying that when students graduate from high school, "the most daunting challenge can be the cost of college." He urged state governments to spend more money on their universities and colleges. The president also proposed shifting federal funds away from higher education institutions that do not stabilize tuition rates while providing a good value, although no more specifics were outlined for that proposal.

He pushed for the doubling of the number of work-study jobs in the next five years. And Obama asked Congress to permanently extend tuition tax breaks that offer up to $10,000 for four years of college and to stop an impending 100 percent increase of the interest rate of federal student loans

Asked for a timetable for the president's proposal, Education Department spokesman Daren Briscoe said that "work is afoot" on developing more specific policies, but could not provide any further information. "Stay tuned," he said.