(TC writer here) I'd say send an email, and if you don't get a response in 1-2 days send one more saying that if you don't hear back in the next 24 hours you'll probably try your luck elsewhere. Don't be threatening about it (the reporter doesn't owe you anything), just be transparent.

Setting a 'time limit' like this helps makes sure you don't end up on the reporter's mental backburner indefinitely. Of course, if the reporter is super swamped this may lead them to simply pass on the story. But usually if it's good, they'll try to find another writer who can take it.