PHOENIX -- Gov. Janet Napolitano on Tuesday vetoed a bill partly intended to help combat illegal immigration by going after day laborers and those who hire them.

The bill would have made it a misdemeanor trespassing offense for day laborers to seek work on public streets and sidewalks and for people who offer or solicit day labor work on private property after the owner asks them to leave.

Day laborers, many of whom are illegal immigrants, gather on street corners, near home improvement stores and other places to seek short-term construction and landscaping work.

Legislative opponents of the bill said communities -- and not the state -- should decide whether they want to impose such rules on day labor and that day laborers provide consumers with easy access to labor. Bill supporters said many people who use day labor break the law by hiring illegal immigrants, indirectly encouraging them to enter the United States.

Napolitano's letter explaining her veto was not immediately available, but her chief lobbyist, Mike Haener, confirmed that she vetoed the bill.

The bill's sponsor, Republican Rep. John Kavanagh of Fountain Hills, reacted to the veto by saying the bill would have protected public safety by reducing traffic disruptions from laborers seeking work.

"The governor is the illegals' best friend with her numerous vetoes," Kavanagh said in a statement.

Napolitano in 2006 vetoed several Republican-sponsored bills targeting illegal immigration. Those included one to make illegal immigrants' presence in Arizona a trespassing offense and to impose sanctions on employers who hire illegal immigrants. She criticized those bills as, respectively, a burden on local governments and ineffective.

The House and Senate approved Kavanagh's bill nearly along party lines, with only one Democratic representative voting for it.