Today Senators Ted Cruz (R., TX) and Mike Lee (R., UT) introduced S. 2024, the State Marriage Defense Act. According to the press release the bill "respects the definition of marriage held by the people of each state and protects states from the federal government’s efforts to force any other definition upon them. The bill will ensure the federal government gives the same deference to the 33 states that define marriage as the union between one man and one woman as it does to the 17 states that have chosen to recognize same-sex unions."
The measure is similar to one introduced last month by Rep. Randy Weber (R., TX), also called the State Marriage Defense Act.
It's unclear why lawmakers would use the word "defense" in their titles, given that that particular word was used by the Supreme Court in U.S. v. Windsor to demonstrate evidence of moral disapproval. Thus, if lawmakers continue with these bills, they may want to think about changing the names...in case they ever reach the Supreme Court.