Three losing bidders have filed a protest over the state’s selection of vendors for a multibillion-dollar Medicaid and PeachCare contract.

Last month, four companies – Amerigroup, Peach State, WellCare and CareSource — were picked as winners of the contract to serve lower-income adults and children in Georgia.

The contract for the “Care Management Organizations’’ is worth an estimated $4 billion over six years. The launch date for the new contract is July 1.

But unsuccessful bidders Americhoice (a unit of UnitedHealthcare), Humana and AmeriHealth Caritas have appealed that decision by the Department of Administrative Services, which handles contracting in Georgia.

Protests of big state contracts are not unusual. Two years ago, United filed a strongly worded protest of the awarding of a state employees benefits contract, alleging that Georgia officials “rigged’’ the bid in favor of a competitor.

In their protests, Americhoice and AmeriHealth Caritas each said the Department of Community Health changed the committee analyzing the bids in the middle of the evaluation process.

Attorneys for Americhoice said the scoring of the bids was “arbitrary and inconsistent.’’

The protests called for the current contract award to be halted and that a new evaluation take place.

The Department of Community Health, which runs Medicaid and PeachCare in the state, declined comment on the bid protests, citing the ongoing appeal period.

Neither Community Health nor Administrative Services gave a timetable for the resolution of the protests.