Phil Donahue’s return to TV is a disaster!

Ratings for his new prime-time MSNBC show quickly plummeted, and soon after its debut, critics declared it was headed straight for the trash heap.

They blast Phil’s style as too old-fashioned and say he doesn’t work well without a studio audience.

His sudden downfall has left the amiable 66-year-old talk show pioneer “devastated and humiliated,” reveals an insider.

Launching his new live show on July 15, Phil achieved respectable numbers against the competition.

Donahue drew 1.1 million viewers — more than half of Bill O’Reilly’s normal 2.1 million for his top-rated “The O’Reilly Factor” on FOX News.

But by week’s end Donahue crashed and burned as half his viewers vanished. In the key 8 p.m. time slot, he also fell behind CNN’s Connie Chung for the week. She averaged 710,000 viewers to Phil’s 660,000.

The first show of his second week saw Phil mired in third place — again behind Chung and O’Reilly.

New York Post media editor Michael Shain told The ENQUIRER he predicts Donahue’s show won’t last the summer.

“It’s just a disaster. He may have invented the modern talk show, but it’s progressed far beyond him.”

Donahue is “just not the kind of high-energy circus performer that makes it on TV today,” declared Bill Mann, syndicated TV columnist and humor columnist for “CBS MarketWatch.”

“And seeing him without a studio audience is like watching Dana Carvey without a funny accent.”

Donahue’s lovely actress-wife Marlo Thomas has been his most vocal supporter, according to the insider.

“Marlo is fighting mad and trying desperately to rally the troops. She’s been calling network execs, asking them to find some way to help him out.”

But USA Today critic Robert Bianco, called “Donahue” the “least watchable” of the 8 p.m. cable shows.

“Donahue has always been preachy,” said Bianco, “but the sermons are now delivered in a voice that makes you think he’s imitating Phil Hartman imitating him.”

It’s a sad final bow for a genuine TV giant.

Before retiring six years ago, Donahue had a staggering record of success. He won 20 Emmys over 29 years and more than 6,000 shows.

But concludes TV critic Mann, “His time has passed.”