WASHINGTON — President Obama will offer a series of proposals this week aimed at making college more affordable by reshaping the way Americans pay for higher education, he said in an e-mail to supporters on Tuesday.

In the message, Mr. Obama promised to take action to confront the financial challenges facing an increasing number of students and their families. The average tuition at four-year colleges has tripled over the past three decades, and students who take out loans are left, on average, with $26,000 in debt, he said.

“To create a better bargain for the middle class, we have to fundamentally rethink about how higher education is paid for in this country,” Mr. Obama said. “We’ve got to shake up the current system.”

The president did not reveal his proposals in the e-mail, and aides at the White House declined to provide details before Mr. Obama embarks this week on a two-day bus tour through upstate New York and Pennsylvania. They said Mr. Obama would talk about his plans in a series of speeches and town hall-style meetings at universities.