The Russian is in the frame to take the second Campos seat currently occupied by Hugo Valente, who is contesting six rounds of the 2013 championship.
Karamyshev currently sits second in the SMT class of this year's European Touring Car Cup, having won once at Monza.
AUTOSPORT understands that Ukranian Igor Skuz, who drives for Campos in the S2000 class of the same category, is the other driver in contention for Moscow and the following round at Porto.
Karamyshev told AUTOSPORT's new Russian site that he was confident of a deal, saying: "Initially [Campos] planned to place another driver in, but he had some issues with budget.
"We have reached an agreement on two events, in Russia and Portugal.
"I have some experience with turbodiesel Leon, and we plan to do some tests for me to get used to the petrol car, which is more powerful.
"My target is not simply to reach the chequered flag. No doubt the championship leaders are very fast, but I'll try my best to be competitive and to fight with guys from the smaller teams.
"I know the circuit quite well as I've already driven there in national championship races last year, and this for sure will help me."
Twelve Russian drivers have to date competed in the WTCC. Aleksei Dudukalo, who lost his Lada drive after an opening-round crash at Monza, is the only man to claim a podium finish at Slovakia last year.
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