(NewsCore) – Rick Santorum is expected to announce he is suspending his campaign for the Republican presidential nomination at an event in Gettysburg, Pa., Tuesday, FOX News Channel reported.

Santorum was scheduled to hold a press conference at the Gettysburg Hotel at 2 p.m. ET.

The event comes amid growing pressure on the former Pennsylvania senator to drop out of the race and back the Republican front-runner, Mitt Romney.

Santorum’s chances for the nomination had dimmed considerably following Romney’s decisive sweep of the Wisconsin, Maryland and Washington, D.C., primaries last week. The former senator fueled further speculation about his possible exit from the race by leaving the campaign trail for several days over the long holiday weekend.

Here’s more about Isabella and a bit about Trisomy 18, her genetic condition:

Santorum’s daughter to leave hospital

Former Sen. Rick Santorum’s daughter Isabella was released from the hospital Monday night, a spokesman tells CNN. The GOP presidential candidate interrupted his campaign Friday, when his 3-year-old daughter was hospitalized for reasons the campaign did not disclose.

Isabella suffers from a chromosomal disorder called Trisomy 18, where extra genetic material is present on chromosome 18. The extra material interferes with normal development, according to the National Institutes of Health.

“We appreciate the outpouring of support and prayers,” said spokesman Hogan Gidley. “The prayers worked, she’s doing much better, so we’re thankful for that.  It puts things in perspective.”

Santorum expects to return to the campaign trail Tuesday.

Santorum has been outspoken and candid about his family’s struggle against Trisomy 18, as he did when he sat down for a Red Chair interview (above) with CNN back in November.

Trisomy 18 occurs in about 1 in 5000 live births, according to the NIH, but many fetuses with this disorder do not survive a full pregnancy.

The NIH describes Trisomy 18 as “a relatively common syndrome,” which is 3 times more likely in girls than in boys. It causes severe developmental and medical problems, including heart defects and defects to other organs prior to birth, shortened breast bones and club feet. Unlike Down syndrome, where a child has 3 copies of chromosome 21, developmental issues in Trisomy 18 are linked to medical complications that are more potentially life-threatening in the early months and years of life, according to the Trisomy 18 Foundation.

Children with Trisomy 18 sometimes can’t cough or clear their throat so fluid will accumulate in the lungs, making them susceptible to respiratory failure.

In the past, Isabella has had pneumonia in both her lungs.

About 90% of children born with Trisomy 18 die within their first year of life, but a small number have gone on to reach adulthood into their 20s and 30s, although they’ve been severely impaired.

“She has a disorder called Trisomy 18, which we were told is incompatible with life,” Santorum told CNN in November. “Well, we’re showing that that’s not only not true, but it is really the center of our life.”