Country’s reigning power couple – BLAKE SHELTON & MIRANDA LAMBERT – may be on a collision course for a dirty divorce!

The National ENQUIRER has learned Miranda had “an ugly confrontation” with her hunky hubby, who’s gained legions of new fans since joining NBC’s hit singing competition, “The Voice,” as a coach.

“Blake blind-sided Miranda by declaring on national TV that they aren’t planning to start a family!” a source said.

The shocker unfolded on Sept. 15 when talk show host Ellen DeGeneres asked: “Blake, will you be reproducing soon?”

The country stud hemmed and hawed before saying, “Ah…I mean…no!” Surprised, Ellen said, “I respect that, but no?”

Blake confirmed with another “No,” but that was “far from the message” he’s been sending at home, revealed a pal.

“Miranda was absolutely floored!” the friend confided.

“She believed the only thing to save their marriage was a baby – and now it’s not happening. On top of that, her good pal Carrie Underwood is now pregnant, and that’s only rubbed salt in the wound.”

If the pair split, it could turn ugly fast. The two – who collaborated on the hit song “Boys ‘Round Here” – are worth an estimated $40 million. Blake also has a $10 million-a-year contract with “The Voice.” And with one failed marriage already under his belt after divorcing first wife Kaynette in 2006, Blake has given Miranda, 30, ammunition for a divorce with his flirty ways. The strapping hunk, 38, was rumored to have had an affair with 25-year-old singer Cady Groves last year.

While Blake denied he cheated, The ENQUIRER reported Miranda was so jealous that she phoned the “other woman” and unloaded on her.

“Now the latest showdown’s been with Blake – and more fireworks will come soon,” said the first source.

Miranda’s Las Vegas concerts were due to wrap up Oct. 5, and Blake is wrapping up his tour in L.A. Both artists are wrapping up their concert tours. The insider said: “Their next conversation could be about a divorce!”