President Trump said Monday he fully understands why Steve Bannon, his former chief strategist, wants to challenge a handful of establishment-friendly Republicans in 2018, and said there are several congressional GOP lawmakers who have "really disappointed" his administration.

"I know how he feels," the president said of Bannon, who has been meeting with potential GOP insurgents since he left the White House in August. "There are some Republicans who should be ashamed of themselves. Most of them are really, really great people but you had a few people who really disappointed us.

"So I can understand fully how Steve Bannon feels," Trump told reporters during a Cabinet meeting Monday.

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Bannon returned to the helm of Breitbart News after leaving the West Wing in August. With the help of several allies, the populist media mogul has slowly been seeking out formidable candidates to primary incumbent Republicans in next year's midterm election. Bannon told Fox News last week he plans to target every GOP senator facing re-election except Texas Sen. Ted Cruz, who he described as sufficiently conservative.

"Steve is very committed. He's a friend of mine," Trump said of Bannon. "I have great relationships with many senators but in particular with most Republican senators. But we're not getting the job done and I'm not going to blame myself, to be honest."

"They're not getting the job done and I can understand where Steve Bannon is coming from," the president told reporters.