Sorafenib may stop the growth of tumor cells by blocking blood flow to the tumor and by blocking some of the enzymes needed for cell growth. Estradiol can cause the growth of breast cancer. Hormone therapy using anastrozole may fight breast cancer by blocking the use of estradiol by the tumor cells. Sometimes when hormone therapy is given, it does not stop the growth of tumor cells. The tumor is said to be resistant to hormone therapy. Giving sorafenib together with anastrozole may reduce drug resistance and allow the tumor cells to be killed. This phase I/II trial is studying the side effects and best dose of sorafenib when given in combination with anastrozole and to see how well they work in treating postmenopausal women with metastatic breast cancer.