The explosive charge comes from Ronald Kessler, author of the new book, "In the President's Secret Service," in which Kessler reveals many previously unknown inside info told to him by agents themselves.
The Secret Service denies Kessler's assertion.
On "The Early Show" Tuesday, Kessler said such routine moves as using metal detectors until everyone attending a presidential or vice presidential event has entered are being curtailed, and someone carrying a weapon could sneak it in.
Kessler also told co-anchor Harry Smith about incidents from the personal lives of first families, among other things agents see and hear.
He also said Mr. Obama is still smoking "on a regular basis," despite the president's protestations to the contrary.
"Some agents were absolutely outraged that the Secret Service has been cutting corners lately, to the point where they'll actually shut down metal detection when an event is about to start and there are stragglers or even, in the case of Joe Biden, when he threw the first pitch at the Orioles game, they'll have no metal detection," Kessler told Smith. "That means that gunmen, terrorists, can bring in weapons, can bring in grenades, and they will not be detected. So, they're really takng a chance with the president's life."
"It's sort of hard to figure" whether the cutbacks are just about budget, Kessler observed, adding, "It's the culture which has started since (the Department of) Homeland Security took it over. It is partly budget. They should get much more money. They're overworked. But also, it's just a corner-cutting culture, and yet the threats are up 400 percent since (Mr.) Obama became president."
"That is a sea change," Smith pointed out, "in terms of an African-American president and all he history he made, but it also makes a huge difference in terms of his day to day protection."
"It's scary," Kessler agreed, "and the Secret Service has not really changed to take account of that, because they're cutting corners."
Would he go so far to say that you think, because of these budget cuts, the president's life might be at risk?
"Oh, there's no question his life is in danger. How basic can it be that they don't do metal detection when you go to an airport? Everyone goes through a metal detector. When George Bush was in the country of Georgia, someone got through with a grenade because metal detection was shut down. It's exactly the same thing, the same chance. Tomorrow, (Mr.) Obama could be assassinated, Biden could be assassinated, simply because the Secret Service was not doing what it used to do until Homeland Security took it over."
The Secret Service says Kessler's allegations aren't true. "The Secret Service assisted Mr. Kessler as we would any author writing a book about the agency," the denial states. "We provided briefings, on the record interviews and accurate responses to his numerous questions. However, Mr. Kessler chose to base his criticisms of the agency on unnamed sources whose motives, knowledge and experience level remains unknown.
"Any suggestion that the Secret Service has "cut corners" in carrying our protective mission is just false. It is always difficult to defend your record against anonymous sources. However, it should be noted that we currently dedicate more personnel, funding and technical assets to our protective mission than at any time in our history and our protective measures and methods continue to increase in scope and complexity, not diminish.
"The safety of those we protect remains this agency's highest priority. Failure is not an option."
To read an excerpt of "In the President's Secret Service," click here.