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I have signed a contract to work for a company. Due to some management issue on their side, the start date has been delayed for a month or two. Even though a company is very responsive to my queries, we still don't know when the exact start date will be.
During that time, I am approached by the second company to interview for a senior position. The interview is successful and I am now offered a position which pays a lot more than the one offered by the first company.
Personally, I still want to work for the first company, better location and more interesting projects, but prefer to renegotiate in order to have a better salary. Hence, my question is whether it is possible and professional to contact the first company, let them know that I want to renegotiate the salary since there is another company that offers me a better one.