(CNN) Rep. Elizabeth Esty, who has apologized after she kept on a top aide for several months despite having learned of abuse allegations against him, said Friday that she has no plans to resign.

"For those who have asked, I want to be clear that I am not resigning," Esty said in a statement to CNN. "I have important work to do in Congress including building on the lessons of this horrible series of events."

Esty, a Connecticut Democrat, entered into a nondisclosure agreement with her former chief of staff Tony Baker and wrote a reference letter for him even after learning of allegations that he had threatened and physically assaulted another aide of hers with whom he was once in a relationship, CNN has confirmed

"My agenda going forward will include relentlessly pursuing specific actions to foster a better working environment on Capitol Hill, building on the work that has already been done to ensure safe environments for staff, looking to the best practices that have been developed in the private sector, and taking the next steps to further strengthen workplace protections and provide employees with a safe platform to raise concerns," Esty said in the statement.

Esty, who has championed the #MeToo movement on Capitol Hill, kept Baker on her payroll for three months after learning of the accusations against him, CNN has confirmed. The Washington Post previously reported the news, citing documents Esty provided.

Andrew Ricci, a friend of Baker's, confirmed to CNN that the staffer, Anna Kain, took out a restraining order against Baker.

"I am sorry that I failed to protect her and provide her with the safe and respectful work environment that every employee deserves," Esty said in an earlier statement, released Thursday.

"To this survivor, and to anyone else on my team who was hurt by my failure to see what was going on in my office, I am so sorry," she wrote, adding, "I must do better."

Esty said in the Thursday statement that she was "horrified" and "angry" to learn that Kain had been allegedly "harassed and harmed" by Baker. She wrote that when she learned of the allegations, she demanded Baker receive counseling and launched an internal investigation.

The Washington Post and the Connecticut Post, citing an affidavit for the protective order, reported that Baker called the staffer 50 times on May 5, 2016, and left her a voicemail saying that he would kill her.

In her petition for a restraining order, the staffer accused Baker of punching her in the back and "repeatedly scream(ing)" at her in Esty's Capitol Hill office throughout 2014, according to The Washington Post.

Ricci told CNN that Baker does not "dispute" that he took part in abusive behavior -- including sexual harassment and berating -- directed at the staffer, but he denies punching her. Ricci confirmed there was an incident in May 2016, where Baker -- either during or after a happy hour drinks event at a bar in Washington -- called the staffer and left an abusive and threatening message.

However, "he was very, very intoxicated and he doesn't remember leaving that message," Ricci told CNN, adding that Baker has since sought counseling as well as anger management and has been sober since May 2016.

In a statement provided to CNN by Ricci, Baker said: "In 2016, Elizabeth was the only person who stopped to ask me how I was doing and urged me to get help beyond just becoming sober. I immediately sought comprehensive help, which has been invaluable in my life of recovery. I have a lot of respect for Anna and I agree that stories like hers need to be told."

In a statement to CNN, Kain criticized what she said was a "flawed system designed to protect powerful people and that isolates and ignores those who need protection most" and called on the Senate to pass laws to further address abuse and harassment in congressional offices.

"If you work on the Hill and are going through this, I want you to know that it's real, it's a problem, and nothing about it is OK. I hear you and I believe you. It is not your fault and you are not alone. And you are stronger than you think you are," Kain said.

Esty said in her statement that when she learned of the allegations, she "demanded counseling for my offending chief of staff and I launched an internal review of management policy and practices and an investigation into what was going on in the office. I also took a hard look at how I allowed my office to be run.

"Unfortunately, through the review process I learned that the threat of violence was not an isolated incident, but part of a pattern of behavior that victimized many of the women on my staff. At which point, I hired a new chief of staff, made changes to senior staff, changed employment policy, and instituted mandatory harassment trainings."

Esty acknowledged to media outlets that she wrote a reference letter for Baker and entered into a nondisclosure agreement at what she said was the recommendation of the Office of House Employment Counsel.

The Office of House Employment Counsel declined to comment on the matter, citing its role in providing confidential employment advice to House offices.

Ricci confirmed to CNN that Esty and Baker, as part of the severance agreement, had agreed upon a reference letter that the congresswoman would use if ever contacted by Baker's potential future employers.

Ricci, however, said it was not a letter that Baker was in possession that he could share with future employers. Rather, it was a letter that Rep. Esty "would go by to describe (Baker's) skills," Ricci said.

According to the Connecticut Post, Baker also received $5,000 in severance, which Esty said she repaid to the US Treasury.

Baker moved on from Esty's office to work for the gun-control group Sandy Hook Promise, according to the Post. Esty told the Connecticut Post she did not find him the position with the organization, but had provided a "limited" recommendation in complying with the nondisclosure agreement. Both news outlets reported that Baker has been dismissed from the organization this week.

Ricci confirmed to CNN that Baker had left his job at Sandy Hook Promise, but said it was because "his position was eliminated." Asked if Baker was fired, Ricci said, "You can read into the timing whatever you want," and referred CNN to the organization.

Sandy Hook Promise did not immediately return CNN's request for comment.

The National Republican Congressional Committee called for Esty's resignation Friday morning.

"Elizabeth Esty orchestrated one of the most disturbing Washington cover-ups in recent memory. There is no place for someone who protects abusers in Congress, and she should resign immediately," NRCC spokesman Chris Martin said in a statement.

The committee is also reaching out again to potential Republican candidates it has tried to recruit to run against the congresswoman, a source familiar with the committee's recruiting efforts said.

Two potential candidates being courted are described as having been on the fence, and then passed on running. There are two months until the filing deadline.

Connecticut's top Republican has also called for Esty to step down over the matter, according to the Hartford Courant, though Esty said she has no plans to do so.

"I was not the perpetrator of this," Esty told the Hartford Courant. "I think there's a whole record of what I've accomplished."