take the steam out of (something)

1. To alleviate pressure, tension, or danger from a situation. Barry tried cracking a joke to take the steam out of the argument, but no one heard what he said. The president is meeting with both countries' leaders in an effort to take the steam out of the international standoff.

2. To dampen, lessen, or weaken something, especially that which had been gaining momentum. Her cutting rebuttal certainly took the steam out of my argument. I'm worried that the government's plan is going to end up taking the steam out of the economic recovery.