British Touring Car Championship organising body TOCA has released an invitation to tender for the supply of the series' TOCA engine, which will be used from 2022.
Teams in the tin-top series have an option of running either the unbranded TOCA engine that is built to Next Generation Touring Car specification or developing their own powertrain - so long as "it is from the same 'family' as their chosen model of car".
The current supply agreement expires at the end of the 2021 season ahead of a new five-year term, which will carry through until the close of the 2026 campaign.
A statement issued by TOCA read: "The new contract is set to be awarded in June 2020, to ensure that a cost-effective engine with proven reliability is ready in time for the start of the 2022 season and available for use by any BTCC team."
The organising body has specified a two-litre turbocharged in-line four-cylinder unit that fits all current cars.
A new supplier must also be "simultaneously considering" the integration of hybrid powertrains in the BTCC, which are scheduled for 2022.
In April last year, the BTCC invited parties to declare their interest in the boosted technology following an investigation into push-to-pass systems.
That contract was awarded to Cosworth Electronics, which designed a 60-volt system that weighs no more than 64kg.
In its purest form, the hybrid boost will be available for a maximum of 15 seconds per lap and provide a power gain of approximately 40bhp.
The advent of hybrid systems in the BTCC will also lead to the scrapping of success ballast, with the best-performing cars receiving incremental restrictions on the levels of electrical power available.
Parties are invited to declare an expression of interest in the TOCA engine supply deal between now and a deadline of 20 January.
Get unlimited access to the world’s best motorsport journalism with Autosport Plus