A U.S. State Department official's concerns in 2015 about Hunter Biden's role in a Ukrainian business and the official's claims of being rebuffed by the staff of then-Vice President Joe Biden are going largely unnoticed in the media, former Trump aide Corey Lewandowski said Friday.

Why have mainstream media outlets been giving little attention to the congressional testimony of Deputy Assistant Secretary of State George Kent? Because Kent's concerns may hurt Joe Biden's chances of winning the White House in 2020, Lewandowski charged Friday on Fox News' "The Ingraham Angle."

"We haven't seen any of the mainstream media covering this because this is an attack on Joe Biden," he said. "The liberal left is rallying around Joe Biden. And, the truth is, we know what Hunter Biden has now said: If his father gets elected president, he won't join any foreign boards [and] he won't try and influence his father."

"The liberal left is rallying around Joe Biden." — Corey Lewandowski

STATE DEPARTMENT OFFICIAL TOLD CONGRESS HE RAISED CONCERNS ABOUT HUNTER BIDEN'S UKRAINE DEALINGS IN 2015 BUT WAS IGNORED

Lewandowski said Hunter Biden's no-foreign-entanglements pledge would be like him claiming he would stop slam-dunking over other players if he played pro basketball.

"When it's the Democrats doing this, [the media] turns a blind eye to it," he said. "It's just not going to happen, we know that, so these are just false promises."

Kent, who testified behind closed doors before House committees spearheading the formal Trump impeachment inquiry, told congressional investigators he had qualms about Hunter Biden’s role on the board of the Ukrainian energy company Burisma Holdings.

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The Washington Post first reported details of Kent’s testimony Friday, including his concerns that the younger Biden’s role in the overseas company could complicate U.S. diplomatic efforts with Ukrainian officials, and raised the issue of a possible conflict of interest. Kent also testified he was worried that Hunter Biden’s position would make Ukrainian officials think he was a channel of influence to his father, who was vice president at the time.

A congressional source confirmed to Fox News on Friday that Kent testified that when he brought his concerns to the office of the vice president in 2016, Joe Biden's staff “blew him off” and ignored the issue involving the younger Biden's role at the firm. The Post first reported that staffers said they did not have the "bandwidth" to deal with the issue, as his other son -- former Delaware State Attorney General Beau Biden -- was battling the cancer from which he ultimately died in 2015.

Fox News' Brooke Singman contributed to this report.