White House Staff Secretary Rob Porter (L) reminds U.S. President Donald Trump he had a bill to sign after he departed quickly following remarks at his golf estate in Bedminster, New Jersey U.S.., August 12, 2017

President Donald Trump on Friday defended former White House aide Rob Porter, who resigned this week after multiple, serious allegations of domestic abuse were made public.

"We wish him well," Trump said of Porter, who most recently served as White House staff secretary. "He worked very hard," said the president, before adding that he had only learned of the allegations recently and was "surprised" by them.

The president also stressed that Porter claims he is innocent of the allegations. "I think you also have to remember that. He said very strongly yesterday he's innocent," Trump said.

Both of Porter's ex-wives claim he was physically and verbally abusive to them during their marriages. In 2010, a judge granted his second wife a restraining order against Porter.

That court order ultimately prevented Porter from obtaining a permanent security clearance to work in the White House, forcing him to work under an interim clearance for months.

Still, Trump had only kinds words for his former aide. "We certainly wish him well. Obviously, it's a tough time for him," he said.

Trump went on to say that Porter "did a very good job when he was at the White House," and "we hope he has a wonderful career. Hopefully, he will have a great career ahead of him."

Trump said he and his senior staff were "very sad when we heard about it," adding that Porter, too, is "very sad."

Trump refused, however, to answer a question about precisely when top White House officials, including chief of staff Gen. John Kelly first became aware of the allegations against Porter — and by extension, why Porter was permitted to keep his job despite his failure to pass the background check required to obtain a security clearance.

The DailyMail.com first reported details on Tuesday of the allegations against Porter, based on interviews with both of Porter's former wives. On Wednesday, The Intercept published a photo of Porter's first wife, Colbie Holderness, with a black eye that she says Porter gave her on their honeymoon.

Porter's second wife, Jennifer Willoughby, also said he physically and verbally abused her, ultimately leading to her application for a restraining order against him in 2010. Holderness and Willoughby have both since confirmed these accounts to NBC News.

In a statement Wednesday, Porter called the allegations false, outrageous and "vile," adding that he "will not further engage publicly with a coordinated smear campaign."

On Thursday, however, White House Deputy Press Secretary Raj Shah admitted that mistakes were made in the handling of Porter's resignation. "I think it's fair to say we all could have done better over the few hours or last few days in dealing with this situation," Shah told reporters.