The White House is warning that time is running short for immigration reform.  Presidential spokesman Jay Carney chided fence-sitters in the U.S. House.

"The merits of moving forward on comprehensive immigration reform are strong enough to compel lawmakers to get off the fence and get it done," he said.

In a meeting with law enforcement officials, President Obama said a window of opportunity is closing as lawmakers devote more attention to November's midterm elections.  

The Senate approved a sweeping, bipartisan measure last year but the bill has gone nowhere in the Republican-led House.  

Carney said the White House remains hopeful and continues pressing the case with House leaders.