The idiom ‘in the running’ means to be a competitor in a competition or contest. To be in with a chance of winning the prize.
Origin: Horse racing.
An example of the idiom ‘in the running’ used in a sentence:
Is Ania in the running for that promotion? No, her manager doesn’t feel that she is up to the job.
The opposite of in the running is out of the running. Meaning someone or an animal that is no longer a viable contender.