Fed Chair Janet Yellen says a hike in the minimum wage would likely have some negative effects on jobs.

Testifying before a Senate committee, Yellen said it's not clear how large that effect would be.

"It's a question mark exactly how large that impact is with different studies coming up," she said. 

Yellen did say a boost in the minimum wage would benefit some people. But she also said it could affect unemployment.

"It's likely to have some negative effect on jobs," she said. 

President Obama has been pushing hard for a hike in the minimum wage.  The federal minimum wage has been at seven-25 an hour since 2009.