Donald Trump Jr is going all in with his support for Eric Greitens, the embattled GOP candidate vying for his party’s nomination to the US Senate in Missouri.

       The eldest Trump family scion posted a video of him at a shooting range with Mr Greitens on Monday. “Never skip range day,” Mr Trump Jr quipped in a caption.

       The video was also shared by the candidate himself, who claimed that the pair was “striking fear into the hearts of liberals, RINOs, and the fake media.”

       In order to do battle with liberals and the media, Mr Greitens will first have to win his state’s GOP Senate primary in August. The field is crowded, but has largely narrowed down to three frontrunners including the former governor.

       Weighing down his bid is an allegation from his ex-wife of abuse and “coercive” behaviour towards her and their children. Mr Greitens has strenously denied wrongdoing, and refused to drop out of the race even as he blames his ex-wife for taking part a “political hit job”.

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       Even so, he faces the daunting task of convincing voters in the primary that he has the capacity to win a general election, which in itself could be a challenge due to the misconduct claim.

       Recent polls show the race split almost evently between the three top candidates: Mr Greitens, Congresswoman Vicky Hartzler, and the state’s Attorney General Eric Schmitt.

       If the misconduct allegation from his wife wasn’t enough, Mr Greitens also has a fair amount of other political baggage in the form of a 2018 sexual assault allegation from a hairdresser and a felony indictment that same year for charges of computer tampering related to a campaign finance case. Those charges were eventually dropped.

       In a statement earlier this month a defiant Mr Greitens declared “I will win”, and vowed to remain in the race.

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       Despite that, the state’s GOP treasurer and other national Republicans have called on the former governor to drop out of the race, but he appears to be making a judgement that the endorsement of Donald Trump Jr.

       His father, meanwhile, has not endorsed in the race but has urged Missouri voters to give Congressman Billy Long, one of the lower-ranked contenders, a second look.