After an ambitious New York gallery announced in 2021 that it would sell Hunter Biden’s paintings for as much as $500,000, some ethics experts and House Republicans expressed concern that such high-priced works from a novice artist could become a conduit for those seeking to influence his father, the president.

Now, as Joe Biden leaves the White House and his son faces the prospect of prison, there are questions as to whether Hunter Biden’s art market, which never reached the heights first projected, is fizzling.

His contract with the gallery has expired, his customer base has remained small and his father, whose stature as president helped fuel interest in Mr. Biden’s work, will soon have a much lower profile.

“Over time, I think his market will probably wash away,” said Charlie Horne, president of Gurr Johns, an art valuation and advisory firm. “His cachet will be short-lived. I don’t think he’s ever gotten real traction.”

Just 10 people bought Biden paintings from the Georges Bergès Gallery that had been representing him in recent years, according to testimony at a Congressional hearing earlier this year. One of them, Kevin Morris, a Hollywood lawyer and a friend of Mr. Biden, bought 11 works for $875,000, or more than half of the roughly $1.5 million gained from the sales, according to the testimony, in January. There have been no indications of any sales since then.