Washington (CNN) Former White House chief strategist Steve Bannon said Sunday he regretted not responding sooner to comments attributed to him that were critical of Donald Trump Jr. in an explosive new book on the White House.

"Donald Trump, Jr. is both a patriot and a good man," read Bannon's statement, which CNN obtained Sunday from a source close to Bannon. "He has been relentless in his advocacy for his father and the agenda that has helped turn our country around."

The statement later adds: "I regret that my delay in responding to the inaccurate reporting regarding Don Jr has diverted attention from the president's historical accomplishments in the first year of (Trump's) presidency."

Bannon's statement comes as the President has called on friends and allies to choose between him and Bannon, a source told CNN. It also comes amid an effort to oust Bannon from his position as executive chairman at the conservative news site Breitbart because of his remarks in the book, a person familiar with the matter told CNN.

White House deputy press secretary Hogan Gidley echoed those sentiments aboard Air Force One on Monday, telling reporters that Bannon's attacks on Trump's family members were "repugnant" and "grotesque."

"I don't believe there's any way back for Mr. Bannon at this point," Gidley said when asked to react to Bannon's statement.

In the book, "Fire and Fury," author Michael Wolff quotes Bannon as saying the 2016 Trump Tower meeting between Trump campaign officials, including Trump Jr. and former Trump campaign chairman Paul Manafort, and a Russian lawyer purportedly offering damaging information about Hillary Clinton was "treasonous." The book also attributes statements to him denigrating the President.

CNN has not independently verified all the assertions in Wolff's book.

Bannon said his comments about the Trump Tower meeting were not aimed at Trump Jr., but rather Manafort, "a seasoned campaign professional with experience and knowledge of how the Russians operate. He should have known they are duplicitous, cunning and not our friends."

Following the publication of Bannon's quotes in the book, which went on sale Friday, Trump has called friends and allies to make clear they must choose between him and his estranged former adviser, a source familiar with the calls told CNN. Axios previously reported the calls.

Trump continued to fume privately about Bannon over the weekend despite Sunday's statement, a source inside the White House told CNN, adding that Trump viewed Bannon's semi-apology as "too little and too late."

Trump has also taken to Twitter to attack Bannon, labeling him "Sloppy Steve," and said in a statement released by White House last Wednesday that Bannon had "lost his mind."

On his Sirius XM radio show later the same day, Bannon praised Trump and called him "a great man" -- a comment Trump touted the following morning.

"He called me a great man last night, so he obviously changed his tune pretty quick," Trump said.

The White House has attacked Wolff as well, and an attorney for Trump sent a "cease and desist" letter to him and the book's publisher. The attorney, Charles Harder, also said he sent a cease-and-desist letter to Bannon warning of potential legal action.

After leaving the White House, Bannon returned to his previous position as executive chairman of the right-wing website Breitbart, where he has boosted Trump and select conservatives. But his future there has come into question in the wake of Wolff's book. There has been a "hard push" to convince Breitbart CEO Larry Solov and Susie Breitbart, the widow of website founder Andrew Breitbart, to fire Bannon, a person familiar with the matter told CNN.

Billionaire conservative donor Rebekah Mercer, who owns a stake in Breitbart, publicly rebuked Bannon and said they had not spoken "in many months."

Although Bannon's statement Sunday said his comments in the book were "not aimed at Don Jr.," a quote attributed to Bannon in the book predicted, "They're going to crack Don Junior like an egg on national TV."

Bannon also said in the statement that he continued to believe special counsel Robert Mueller's investigation into potential coordination between Trump's associates and Russia to influence the 2016 election is "ridiculous" in nature and "a witch hunt."

In the book, Bannon is quoted as calling the Trump Tower meeting in June of 2016 "treasonous" and saying it should have been reported to the FBI.

"The three senior guys in the campaign thought it was a good idea to meet with a foreign government inside Trump Tower in the conference room on the 25th floor -- with no lawyers. They didn't have any lawyers," Bannon said in the book. "Even if you thought that this was not treasonous, or unpatriotic, or bad s***, and I happen to think it's all of that, you should have called the FBI immediately."