WASHINGTON — President Barack Obama launched a two-day bus tour through New York and Pennsylvania to promote proposals for making college more affordable, a goal he has cast as “a personal mission.”

Officials said the president will call for changes in the way college is paid for, with the understanding that government assistance alone cannot keep up with skyrocketing education costs. According to Obama administration estimates, average tuition costs at four-year public colleges have more than tripled over the last three decades.

The bus tour, which begin Thursday, underscores the White House’s desire to stay focused on domestic issues, even as foreign policy crises in Egypt and Syria vie for his attention. Obama, in an email to supporters this week, said a big part of middle-class security includes fundamentally rethinking how to pay for higher education.

“Just tinkering around the edges won’t be enough,” Obama said. “We’ve got to shake up the current system.”

The president previously has called for changes in the college funding structure that would move federal financial aid away from colleges that fail to keep tuition down and toward those that take steps to keep costs in check.

He also has proposed a $1 billion college “Race to the Top” competition that would reward states that make significant changes in higher education policies while also containing tuition costs.

The backdrop for the president’s rollout will be colleges and high schools throughout New York state and Pennsylvania. He held his first event Thursday morning at the University of Buffalo before traveling by armored bus to Henninger High School in Syracuse, N.Y.

The president will hold a town hall Friday at Binghamton University, then travel to Scranton, Pa., for an event at Lackawanna College.