Opposition leader Isaac Herzog responded on Thursday a day after the attorney-general instructed law enforcement to conduct an initial probe into his possible violation of campaign finance laws. "We are not suckers and we understand well why such a thing happened, and who stands behind it will receive a political blow that will teach him a lesson that he will not forget for many years," Herzog said at a Tel Aviv convention of labor branch heads. "There will always be those who try to topple you and to use the police as part of their campaign. We know such tactics and we have dealt with them before and we will respond with full force to any attempt to use the police against us. "I am not worried from any probe and I will cooperate with any process. The charges are ridiculous and they are intended to deter me from running and leading the Zionist Union," he said. "But I will run. I will win. And I will make sure that whoever used this approach will regret it," he added.