President Barack Obama said today that the federal government will monitor Arizona’s tough new state measures on immigration that he said “threatens to undermine basic notions of fairness that we cherish as Americans.”

Speaking at a Rose Garden ceremony, Obama said the bill, which Gov. Jan Brewer must decide today whether to act upon, could also undercut trust between police and local communities.

The sweeping measure would make it a crime under state law to be in the country illegally. It would also require local police officers to question people about their immigration status if there is reason to suspect they are illegal.