Saying tens of thousands of Iowans face higher payments on their college loans if nothing is done, the White House laid the groundwork Monday for President Barack Obama’s trip to Iowa City this week, arguing that keeping college costs down will pave the way to the middle class for millions of Americans.

The president will be at the University of Iowa on Wednesday, seeking to make the case that the 2007 law that cut interest rates in half for subsidized Stafford student loans should be extended past its scheduled expiration date in July.

“President Obama believes that we must reward hard work and responsibility by keeping interest rates on student loans low so that more Americans get a fair shot at an affordable college education, the skills they need to find a good job and a clear path to the middle class,” Cecilia Munoz, White House domestic policy adviser, said on a conference call with reporters Monday.

Currently, interest rates on the subsidized loans are 3.4 percent. That authority expires in July, which would push the interest rate on new loans to 6.8 percent.

The White House says the boost in interest rates would cost students almost $1,000 over the life of their loans.

More than 255,000 students in Iowa have such loans, the administration says. Figures from the Iowa College Student Aid Commission, however, said only about half that many got subsidized Stafford loans in the 2010-11 academic year. The reason for the difference wasn’t immediately clear.

Nationwide, 7.4 million students would be affected, the White House said.

The president’s visit to Iowa City is one of three stops he’s making on college campuses to push the proposal. All are in swing states for the 2012 election. The other stops are in Colorado and North Carolina.

The White House also said it would begin pushing its proposal, using social media such as Facebook and Twitter.

College costs are important to many Iowans, and the average debt load for graduates in the state is among the highest in the country.

At Iowa State University, Iowa students graduated with an average debt of $29,035, according to the state Board of Regents. At the University of Iowa, it was $24,652, and at the University of Northern Iowa, it was $25,435.

The president has argued for lowering college costs, including in his State of the Union address. He’s expanded the maximum Pell grant to $5,635 for the 2013-14 year and has proposed expanding the American Opportunity Tax Credit program. Munoz said the administration has spoken with governors and colleges to try to keep costs down.

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Republicans have been critical of the president’s plan to extend the low interest rates. Citing a Congressional Budget Office study, they said it would cost $6 billion a year.

Last week, a top House Republican said extending a policy based on campaign promises is a mistake. And on Monday, a spokesman for the Republican National Committee said the president is seeking to divert attention from his record.

“In 3.5 years in office, President Obama has done nothing as student debt and tuition rates have soared while about half of college grads under 25 are unemployed or underemployed,” Ryan Mahoney said in a statement. “More phony and divisive rhetoric will not change the fact that this president has utterly failed young Americans struggling in the Obama economy.”

The trip is an official visit, not a campaign trip, the White House says. Munoz said the president is traveling the country to press his message because the issue is important to Americans.

“This is the people’s business,” she said. “The reason the president will be traveling around the country talking about this issue is because this is important to our country’s economic future, and it’s important to making sure college remains affordable in this country.”