Washington (CNN) President Donald Trump is growing frustrated that his administration is facing the prospect of another contentious confirmation battle as the President and his aides scramble to shore up support for Gina Haspel, Trump's pick to run the CIA, several sources tell CNN.

Trump stepped up his involvement in the rescue effort Saturday when he spoke with Haspel by phone, according to a source with knowledge of the conversation. The call came a day after Haspel offered to withdraw her nomination -- an offer she walked back after conversations with White House legislative affairs director Marc Short and Sarah Sanders, the press secretary.

During the phone call, Trump dismissed concerns about Haspel's role in past interrogations of suspected terrorists and voiced support for her nomination, a separate source said. Trump reiterated his support of Haspel in a Monday morning tweet.

Meanwhile, Haspel was on Capitol Hill Monday making the case for herself. She was scheduled to conduct multiple meetings with lawmakers who could decide her fate, a White House aide said. Those meetings included time with West Virginia Sen. Joe Manchin, a red-state Democrat whose vote is seen as crucial to her confirmation.

After meeting with Haspel for about 45 minutes, Manchin said he's "very open-minded" about her nomination and has a "curiosity" to hear what his other colleagues have to say and how she responds to questions during a confirmation hearing slated for Wednesday.

Read More