U.S. President Donald Trump defended the "history and culture" represented by statues of Confederate leaders early Thursday, even as the descendants of one southern general called for the removal of a memorial to their great-great-grandfather.

Confederate statues are "overt symbols of racism and white supremacy, and the time is long overdue for them to depart from public display," wrote Jack and Warren Christian, descendants of Thomas (Stonewall) Jackson, in an open letter to officials in Richmond, Va.

We are ashamed of the monument. – Jack and Warren Christian

The letter, which was published late Wednesday by Slate, lauds some of Jackson's behaviour while condemning his ownership of slaves and his decision to fight for the South.

"While we are not ashamed of our great-great-grandfather, we are ashamed to benefit from white supremacy while our black family and friends suffer. We are ashamed of the monument," the Christians wrote.

An equestrian statue of Jackson is one of several memorials to the Confederacy that line Richmond's Monument Avenue. They have been the subject of debate among city officials, according to local media, after a deadly clash between protesters over the planned removal of a similar monument in Charlottesville, Va. Richmond was the capital of the Confederacy for most of the the four-year Civil War.

You can't change history. — Donald Trump

Confederate monuments have been torn down, dismantled and covered up this week in Baltimore, Md., Birmingham, Ala., and Durham, N.C. Similar efforts are underway in Lexington, Ky., Memphis, Tenn., and Jacksonville, Fla.

In a series of tweets early Thursday, Trump lamented the loss of "beauty."

"You can't change history but you can learn from it," Trump said via Twitter.

"The beauty that is being taken out of our cities, towns and parks will be greatly missed."

Trump also suggested that the removal of statues commemorating Jackson and fellow Confederate Gen. Robert E. Lee could lead to similar moves against memorials for U.S. founding fathers such as George Washington and Thomas Jefferson.

Sad to see the history and culture of our great country being ripped apart with the removal of our beautiful statues and monuments. You..... —@realDonaldTrump

...can't change history, but you can learn from it. Robert E Lee, Stonewall Jackson - who's next, Washington, Jefferson? So foolish! Also... —@realDonaldTrump

...the beauty that is being taken out of our cities, towns and parks will be greatly missed and never able to be comparably replaced! —@realDonaldTrump

Trump made a similar comparison during a news conference earlier this week when, in a combative exchange with reporters, he suggested there was scant difference between Washington and Jefferson, who both owned slaves, and the leaders of the Confederacy, which went to war with the rest of the U.S. in the 1860s in a bid to preserve slavery.

Trump also suggested during that news conference that counter-protesters and white hate groups at the rally were equally responsible for the violence that left one woman dead, earning rebukes from across the political spectrum.

Among his critics was Sen. Lindsey Graham, a Republican from South Carolina, who suggested Trump had drawn a "moral equivalency between the white supremacist neo-Nazis and KKK members" who attended the rally, and others opposed to such groups.

Trump called Graham's statement "a disgusting lie" and went on to accuse unspecified "fake news" of misrepresenting his comments about hate and bigotry.

Trump's remarks following the violence in Charlottesville have rocked his administration, leading to rising speculation that some top officials may be looking for a way out.

Descendants of Thomas (Stonewall) Jackson say this statue of the Confederate general on Monument Avenue in Richmond, Va., should be removed. (Google)

Later Thursday, Republican Sen. Bob Corker, chairman of the Senate foreign relations committee, questioned Trump's capacity to govern.

"The president has not yet been able to demonstrate the ability or the competence that he needs to be successful," said Corker, who Trump had considered for the job of secretary of state. Corker said Trump needed to make "radical changes."

Sen. Dan Sullivan, another Republican, added on Twitter, "Anything less than complete & unambiguous condemnation of white supremacists, neo-Nazis, and the KKK by (Trump) is unacceptable. Period."

Anything less than complete & unambiguous condemnation of white supremacists, neo-Nazis, and the KKK by the <a href="https://twitter.com/POTUS">@POTUS</a> is unacceptable. Period. —@SenDanSullivan

A parade of business executives broke ties with Trump on Wednesday after he blamed white nationalists and counter-protesters in equal measure for the weekend clashes in Virginia.

Now, frustrated aides could be next. Trump's remarks have left some wondering if sticking by the president comes at too high a cost to their reputations.

"A lot of us joined this administration thinking we could bring to it the experience and expertise that the president didn't have an opportunity to gain in his business career, and to encourage some restraint in what he says publicly and to our allies," said one senior official who is contemplating whether to resign.

"After yesterday, it's clear that there is no way for anyone, even a marine general, to restrain [Trump's] impulses or counter what he sees on TV and reads on the web."

It was hoped that retired general John Kelly, Trump's new chief of staff, could impose some form of discipline on Trump that his predecessor, Reince Priebus, could not.

But Kelly stood with his eyes fixed on the floor when Trump veered off script at his Manhattan office tower on Tuesday.