Eight senators have reached a tentative deal on student loan rates, which doubled on July 1 when lawmakers couldn't reach a deal. The rates will now be tied to interest rates on 10-year Treasury bonds, The New York Times' Jonathan Weisman reports. The rates will be lower than they were on July 1, but higher than they were on June 30.

3.4 percent: The old rate on Stafford loans—which go to the poorest students—that expired on July 1.

6.8 percent: What the Stafford rate rose to on July 1.

3.61 percent: What the Stafford rate for undergrad loans drops to if this deal is signed into law, according to the Times.

5.21 percent: What the grad student rate drops to if the deal goes through.

8.25 percent: The new cap on undergrad rates. 

9.25 percent: The new cap on grad student rates.

Treasury rate + 1.8 percentage points: The new formula for determining Stafford loan rates.

Treasury rate + 4.5 percentage points: The new formula for determining PLUS, a different loan program.

But the deal is not certain. The House has already passed a bill that would tie student loan rates to rates on Treasury notes, NBC News' Kasie Hunt explains, but President Obama threatened to veto it, because it would use the savings to pay down the deficit. Senators are waiting to see if their version would raise the deficit according to a Congressional Budget Office analysis. As The Hill's Pete Schroeder explains, Democrats argued that if the bill would cut the deficit, that means student loan rates could be lowered.