Obama's press secretary slams professional left

White House press secretary Robert Gibbs has taken aim at the "professional left" for being unnecessarily harsh on U.S. President Barack Obama and pushing for a Canadian-style health-care system.

"They will be satisfied when we have Canadian health care and we've eliminated the Pentagon," the normally affable Gibbs says in an explosive interview published Tuesday in the congressional newspaper The Hill. "That's not reality."

Those on the left who claim Obama as president isn't much different than George W. Bush, he added, "ought to be drug-tested."

The remarks sent immediate shockwaves through Washington, particularly among the very liberals who have expressed disappointment with the president since his historic election in November 2008 on a message of hope and change.

By mid-day Tuesday, Gibbs was expressing remorse about his comments in a statement aimed at attempting to explain his frustration at the criticism confronting his boss.