- Federal student loan rates are scheduled to double July 1
- The rate would go from 3.4 to 6.8%
- Democrats and Republicans are divided on how to fund an extension of the lower rate
- Sen. Jon Kyl says Republicans want a Senate vote on their plan
Washington (CNN) -- The fight over a potential doubling of student loan interest rates this summer hits the Senate floor Tuesday with Republicans promising to block a White House-backed plan unless Democrats allow a vote on a GOP alternative.
Interest rates on federal student loans are scheduled to rise to 6.8% from the current 3.4% in July unless Congress acts. But Democrats and Republicans disagree over how to offset the $6 billion it would cost to keep the rates down.
Democrats want to eliminate a tax break for some corporations while Republicans want to pull funds from a preventative health care fund set up under the health reform law.
Arizona Sen. Jon Kyl, the second-ranking Senate Republican, said Monday he believes a tough stand is necessary on this issue and will lead to compromise.
"We'll defeat cloture," Kyl said, using the legislative parlance for a key procedural vote scheduled for Tuesday that requires 60 votes to succeed.
If Republicans prove Democrats can't move a bill without GOP support, "I presume leaders in the House and Senate will get together and find a way to ensure the interest rate doesn't double," Kyl said.
An aide to Senate Majority Leader Harry Reid, D-Nevada, said negotiations over the issue are still under way.
Kyl said Republicans are "really disappointed" Reid has not agreed to hold a vote on the Republican funding alternative.
President Barack Obama, meanwhile, has led a high profile, multi-pronged lobbying push to pressure Republicans to support the Democrats' bill.
On Friday, he urged high school students to e-mail, tweet and teach their parents to tweet a message to Congress.
"We can't price the middle class out of a higher education," the president said. "That's why we've got to make college more affordable."
The Republican-dominated House has already passed a version of the bill -- one that the White House warned late last month would be vetoed by the president if it also clears the Senate. The House version passed 215-195 on a largely party-line vote.
CNN''s Ted Barrett contributed to this report.
