Levi Johnston says ex-fiance Bristol Palin, daughter of Alaska Gov. Sarah Palin, allows him to visit their 3-month-old son but won't let him take the baby out.
In an interview to air on Monday with talk show host Tyra Banks, Johnston, 19, said he and 18-year-old Bristol don't always get along.
"Some days we can have regular conversations without fighting," Johnston said. "Most of the times, I don't know what's wrong with her. She's in a pretty bad mood, she's short, she doesn't want me around, I don't think. She says that I can come see the baby and that kind of thing, but won't let me take him anywhere."
The two are the parents of an infant son, Tripp, born on Dec. 27.
Palin family spokeswoman Meghan Stapleton said Bristol Palin was unaware Johnston would be appearing on "The Tyra Banks Show," along with his mother, Sherry, and sister, Mercede.
"We're disappointed that Levi and his family, in a quest for fame, attention and fortune, are engaging in flat-out lies, gross exaggeration, and even distortion of their relationship," Stapleton said in a statement Friday.
Stapleton has said Bristol Palin isn't preventing anyone from seeing the baby, and that Johnston sees his son "whenever he wants, the family sees the baby whenever they want."
Johnston told The Associated Press on March 11 that the couple had broken off their engagement. He has said they needed time to grow up before following through on marriage plans.
In the interview with Banks, Johnston said the Alaska governor probably knew he and Bristol were having sex. "Moms are pretty smart," he said.
Sarah Palin announced her daughter's pregnancy on Sept. 1, just days after Sen. John McCain picked her to be his Republican vice presidential running mate. Johnston later appeared at the Republican National Convention with the Palins.
Johnston told Banks he went to the convention at Bristol's request, but he wasn't thrilled to attend it. "I felt out of place," he said.
Asked whom he'd vote for in 2012 if the choice were President Barack Obama or the Alaska governor, he said: "I still think I'm going to have to vote for Sarah Palin."