Sens. Jim DeMint (R-S.C.) and David Vitter (R-La.) introduced an amendment to a small business bill that would have barred federal funds from being used in any lawsuit seeking overturn the Arizona law. But the amendment failed on a 43-55 mostly party-line vote.

Arizona’s two Republicans senators, John McCain and Minority Whip Jon Kyl, backed the amendment.

The vote came a day before a federal judge in Phoenix hears oral arguments in the Justice Department’s suit against the Arizona law, known as SB 1070. The law makes it a state crime to be in the country illegally, and requires police officers to check the immigration status of individuals they suspect are illegal immigrants.