The father of Sarah Palin's grandson has another baby on the way - with a 20-year-old teacher, TMZ exclusively reports.

Levi Johnston was hurled into the limelight in 2008 after it emerged he was expecting a baby with then vice Presidential candidate Sarah Palin's daughter Bristol.

The pair became engaged shortly before son Tripp's birth, but ended their relationship after a number of very public feuds.

Johnston, an aspiring actor and model, who later posed for Playgirl magazine, is now in a relationship with Sunny Oglesby.

The new baby is reportedly due in around six months time.

While promoting his book, Deer In The Headlights: My Life in Sarah Palin's Crosshairs, the 21-year-old told Huffington Post in September last year he only sees his son around once a month.

He also claimed Bristol, who was 18 when she gave birth, deliberately got pregnant because she was jealous of her mother's pregnancy.

Palin gave birth to her fifth child, a son named Trig in 2008.

Johnston said: "Bristol was on birth control for a long time. She got off it soon after Trig [Sarah Palin's son] was born. I think Trig was a big motivator for her. Her mother just had a child and I think Bristol was really jealous. She was the one who was supposed to have that kid and that's when she got off of [birth control]. We weren't practicing safe sex and she ended up getting pregnant."

Below, a look back Johnston's time in the limelight with the Palin family, and his famous ex's best (and worst) fashion moments.

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• July 2004 with mom Sarah and sisters Piper & Willow

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• September 2008 in St. Louis, Missouri

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• September 2008 at the Republican National Convention

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• September 2008 with Levi Johnston in Minneapolis

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• August 2008 at an Ohio campaign rally

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• May 2009 at a Candie's Foundation event

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• May 2010 with Drew Pinksy at the "Teen Mom Tell All" conference

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• May 2010 at a Candie's Foundation event

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• July 2010 with Levi Johnston and son Tripp

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• September 2010 at the "Dancing With The Stars" premiere

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• September 2010 in workout gear

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• October 2010 with Mario Lopez

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• November 2010 at "Dancing With The Stars"' 200th Episode

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• November 2010 leaving "Good Morning America"

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• December 2010 on ABC's "Dancing With The Stars"

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• February 2011 at the Reagan Ranch Center

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• April 2011 with her aunt, Molly McCann

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• April 2011 at an MSNBC after-party

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• May 2011 at a Candie's Foundation event

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• July 2011 with Colbie Caillat

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