Phoenix - Anger mounted Thursday over an Arizona measure cracking down on illegal immigration as a police officer sued to challenge it, governors in Texas and Colorado weighed in to oppose such a law in their own states, and activists in Chicago chanted for a boycott outside an Arizona Diamondbacks game.

The lawsuit from 15-year Tucson police veteran Martin Escobar was one of two filed Thursday, less than a week after Republican Gov. Jan Brewer signed the bill that critics claim is unconstitutional and fear will lead to racial profiling.

U.S. Attorney General Eric Holder has said the federal government may challenge the law, which requires local and state law enforcement to question people about their immigration status if there's reason to suspect they're in the country illegally, and which makes it a state crime to be in the United States illegally.

Brewer and other backers say the state law is necessary amid the federal government's failure to secure the border and growing anxiety over crime related to illegal immigration.

While divisive debate over the law swirled nationwide, Arizona lawmakers were aiming to adjourn their legislative session late Thursday. Before doing so, they were expected to vote on a recommendation from a House-Senate conference committee that would strengthen restrictions in the law on using race or ethnicity as the basis for police questioning. The law's sponsor, Republican Sen. Russell Pearce, characterized those possible changes as clarifications "just to take away the silly arguments and the games, the dishonesty that's been played."

In filing his suit against the law, Escobar, an overnight patrol officer in a heavily Latino area of Tucson, argued that there's no way for officers to confirm people's immigration status without impeding investigations, and that the new law violates constitutional rights.

Tucson police spokesman Sgt. Fabian Pacheco said Escobar acted on his own in suing, and not on the department's behalf.

The National Coalition of Latino Clergy and Christian Leaders also sued Thursday, and sought an injunction preventing authorities from enforcing the law. The group argued that federal law pre-empts state regulation of national borders, and that Arizona's law violates due process rights by letting police detain suspected illegal immigrants before they're convicted.

"Mexican-Americans are not going to take this lying down," singer Linda Ronstadt, a Tucson native, said at a state Capitol news conference on another lawsuit planned by the American Civil Liberties Union, the Mexican American Legal Defense and Educational Fund and the National Immigration Law Center.

At least three Arizona cities - Phoenix, Flagstaff and Tucson - are considering legal action to block the law. In Flagstaff, police investigated a threatening e-mail sent to members of the City Council over their opposition to the law. The author said council members should be "arrested, tried in court, found guilty of treason and hanged from the nearest tree!"

About 40 immigrant rights activists gathered outside Wrigley Field in Chicago Thursday as the Cubs open a four-game series against the Arizona Diamondbacks. A small plane toting a banner criticizing the law circled the stadium, and activist George Lieu said they've sent a letter to Cubs management asking them to stop holding spring training in Arizona.

A Cubs spokesman declined to comment. Arizona manager A.J. Hinch says the team is there to play baseball.

The Mexico-based World Boxing Council said it will not schedule any bouts featuring Mexican fighters in Arizona, to protest what it called the state's "shameful, inhuman and discriminatory" immigration law.

At the University of Arizona in Tucson, a campus-wide e-mail from school President Robert Shelton said families of several out-of-state honor students have notified the university that they enrolled their children elsewhere.