EXCLUSIVE — Led by Sens. Roger Marshall (R-KS) and Shelley Moore Capito (R-WV), 20 GOP senators signed a letter addressed to Food and Drug Administration Commissioner Robert Califf, questioning the administration's lengthy investigation of Abbott Nutrition and demanding answers as to why proactive measures weren't taken to ease the baby formula crisis.

In the letter exclusively obtained by the Washington Examiner, the group explains that "families are getting to the brink of pursuing unsafe and potentially dangerous options to feed their infants including homemade infant formula. And physicians are, once again, running defense on misinformation due to a lack of federal action to get the word out on safe alternatives."

Notably, Marshall is an obstetrics and gynecology specialist and practiced medicine before becoming a senator.

"Abbott Nutrition’s voluntary recall exacerbated the shortage, and yet no policies were taken to mitigate the sharp increases to the current out-of-stock 43 percent the Administration is now scrambling to address," the senators wrote, adding that it's "concerning that FDA and key officials in the Administration did not anticipate this crisis or take action within days following Abbott Nutrition’s voluntary recall considering the company holds 48.1 percent of the U.S. market in infant formula."

Signing the letter are Sens. Susan Collins (R-ME), Mike Braun (R-IN), John Barrasso (R-WY), Kevin Cramer (R-ND), Marsha Blackburn (R-TN), Jerry Moran (R-KS), Lisa Murkowski (R-AK), John Boozman (R-AR), Bill Cassidy (R-LA), Deb Fischer (R-NE), Cynthia Lummis (R-WY), Tim Scott (R-SC), Thom Tillis (R-NC), Cindy Hyde-Smith (R-MS), John Thune (R-SD), James Lankford (R-OK), Roy Blunt (R-MO), and Ted Cruz (R-TX).

The politicians further decried the apparent lack of urgency on the FDA's part and stressed the growing number of families in need.

"The shortage, felt by all families in need, is disproportionately impacting vulnerable populations," they wrote.

"Based on the timeline, it is unclear why federal health agencies have not been able to complete this investigation in a more expeditious manner or plan ahead to mitigate this additional supply chain disruption."

Included in the letter is a list of questions for the administration regarding the timeline of both the shortage and the investigation.

The senators are requesting a response from Califf "no later than Wednesday, May 25, 2022."