Student loan interest rates doubled today, after Congress and President Obama were unable to agree to a deal that would prevent the increase.

Subsidized federal Stafford loans for undergraduate students are awarded to students with demonstrated financial need pursuing a bachelor's degree. Previously, the interest rate had been 3.4 percent, but that jumps to 6.8 percent today.

Only new loans taken out after Jul. 1 are affected, and only subsidized Stafford loans for undergraduates will see rates rise. Loans for graduate students are parents are unaffected. Unsubsidized Stafford loans for undergraduates already bear a 6.8 percent interest rate.

Still, more than 7 million students will be affected by the increased interest rates, potentially adding thousands of dollars to the already expensive price tag of college. Millions of recent graduates are burdened with heavy student loan debt with few job prospects in a relatively bleak economy.

Lawmakers were unable to agree on a solution to the issue. Republicans and Democrats offered fundamentally different solutions and were unable to reconcile their approaches.

Democrats preferred to extend the 3.4 percent rates for another year, as lawmakers did last year, in order to allow more time to find a permanent fix amenable to both parties.

Republicans opted for a permanent solution that tied interest rates to market rates, a plan that would have kept rates low for now, but would have made it impossible to predict the final cost of the loans. Similar interest rate fluctuations contributed to the downfall of the housing market, when homeowners found their interest rates soar far higher than they could afford.

Neither party seriously considered the proposal by freshman Senator Elizabeth Warren, which would have let students take advantage of the low interest rates the federal government offers to banks.

On Jul. 10, the Senate will consider a Democratic proposal to retroactively extend the 3.4 percent rates for another year, but Republicans are expected to filibuster it.