Three years ago, young Sarah Murnaghan was on a ventilator as her Newtown Square family waged a nationally watched fight to get her a lifesaving lung transplant.

Now, she is appearing in a new TV ad for Sen. Pat Toomey (R., Pa.) as he battles for his political career.

"Sarah's parents tried everything. Then, Pat Toomey went to work," a narrator says. "Pat Toomey fought for new organ transplant rules - and won. Now, all children have a better chance at life."

Leading among male voters but trailing badly with women as he opposes Democrat Katie McGinty, Toomey launched the ad Monday, the same day that Sarah, now 14, and her mother, Janet, joined him at a news conference to throw their voices into one of the nation's most critical Senate races.

As is often the case when it comes to political ads, the TV spot leaves out some key details.

It was a federal judge's ruling, not any legislation or congressional act, that ensured Sarah would receive the transplant she needed - a point Toomey acknowledged at the event Monday, although not in the ad.

Before the court decision, the Department of Health and Human Services had declined to act on Toomey's appeals.

Toomey - attacked by Democrats as a Wall Street banker - has for months attempted to portray himself as an advocate for sympathetic causes.

His first TV ad cited a bill meant to crack down on pedophiles hired in schools, and he recently went to the Senate floor with an enlarged photo of a mournful dog to urge a vote on his bill to fight animal abuse.

His newest spot features Sarah riding a bike.

"Sen. Toomey is really, really nice," she tells the camera. "He cares about people, so it would be a good idea to vote for him."

Democrats have tried to drown out Toomey's messages by pinning him to GOP presidential nominee Donald Trump.

At the same time Toomey held his event Monday, McGinty seized on new questions about the GOP presidential nominee, accusing Toomey of ducking critical issues by refusing to take a clear stand on Trump.

She asked if the senator still might support the billionaire after the New York Times reported that Trump declared a $916 million loss on his 1995 tax return, an amount that may have allowed him to avoid paying any federal income taxes for up to 18 years.

"It's time for Sen. Toomey to be frank and clear with voters in Pennsylvania on a pretty simple question: Does the senator support or not support his party's standard-bearer for president of the United States?" McGinty asked on a call with reporters.

Toomey has said he "hopes" to support Trump but isn't yet convinced.

At this stage of the election, McGinty said, that position is "not credible," and his refusal to answer "is disqualifying."

Toomey's staff limited the questioning at Monday's event. Toomey took only six questions and did not mention Trump.

He has tried to keep the focus on his work for the Keystone State.

He and other local politicians got involved with the Murnaghans in 2013 when Sarah, who has cystic fibrosis and was then 10, had just weeks to live.

She faced a months-long wait for a lung transplant, because she was on the children's waiting list and could not get onto the list for adult lungs.

The adult list was limited to people 12 and older, according to rules established by the Organ Procurement and Transplantation Network (OPTN), which sets national transplant policy.

Toomey wrote to the head of the Department of Health and Human Services and gave a Senate floor speech. The department declined to change policy.

Sarah was, however, aided by a court decision suspending the rules and making her eligible to receive an adult lung.

The organ transplant board then changed its rules to allow children to be considered for adult lungs, based on their medical need.

At Monday's news conference, Janet Murnaghan said Toomey helped draw attention and "add real legitimacy" to the family's fight. She added that he visited Sarah in the hospital and offered "support and comfort."

"When the whole thing finished and everybody left, he was still there," pushing for a permanent change to the transplant rules, she said.

Toomey said he sent the message that he would pursue legislation if the transplant board didn't "do the right thing."

In his six years in the Senate, he said, "there's no individual case that's more satisfying to me."

Asked Monday about Toomey's views on Trump and his taxes, Toomey's spokesman responded by praising the senator and attacking McGinty.