There are several viable ways to encourage an employer to raise a salary offer.
1. Explain that you are asking for more money out of necessity, not greed. Cite specific examples as to why a slightly higher salary would be critical toward helping you meet certain cost-of-living expenses. For example, think about your commuting costs. If they are higher, that is a perfect reason to ask for additional compensation.
2. Tell the employer that although you are very interested in the available position, you have also received offers from competitors that are slightly higher. Do not bluff.
3. Explain that the offered salary is on the low end of the industry salary range and that your skills and experience justify a salary that is at least in the middle of that range.