But they questioned whether all of those jobs truly represented the "critical needs" for which direct-hire authority is usually reserved.
"Please explain why there was a 'critical need' for HHS to waive provisions of federal hiring law to hire 90 dental officers to implement the health care law," they wrote.
The letter to OPM also says HHS would have had to hire 10 people per day to fill all of the positions OPM designated as critical.
"The pace of hiring that would be required for HHS to maximize this authority and fill each of those 'critical needs' is incredible," the lawmakers wrote.
In addition to Coburn, the letter questioning HHS's hiring authority was signed by Sens. Richard BurrRichard BurrTrump's pick for intel chief to get hearing next week A guide to the committees: Senate Juan Williams: Senate GOP begins to push Trump away MORE (R-N.C.), Michael Enzi (R-Wyo.), Charles GrassleyChuck GrassleyGOP senator grilled over DeVos vote during town hall Big Pharma must address high drug prices ObamaCare fix hinges on Medicaid clash in Senate MORE (R-Iowa), Kelly AyotteKelly AyotteLewandowski saw no evidence of voter fraud in New Hampshire NH governor 'not aware’ of major voter fraud Former NH AG: 'Allegations of voter fraud in NH are baseless' MORE (R-N.H.) and John ThuneJohn ThuneObamaCare fix hinges on Medicaid clash in Senate A guide to the committees: Senate Verizon, Yahoo slash merger deal by 0M over data breaches MORE (R-S.D.).