Death threat report confirmed By CNN
CNN: Death Threats Against Obama Increase By 400 Percent

A CNN source with very close to the U.S. Secret Service confirmed to me today that threats on the life of the president of the United States have now risen by as much as 400 percent since his inauguration, 400 percent death threats against Barack Obama — quote — “in this environment” go far beyond anything the Secret Service has seen with any other president.

It’s very plausible, it’s been reported and it’s been confirmed. I see no reason to doubt the claim.