Updated

Most American voters believe the federal government is failing to enforce the country's immigration laws, according to a Fox News poll released Thursday. In addition, voters are more likely to favor than oppose Arizona's new immigration law that was in large part blocked by a federal judge this week.

Views on the Arizona law changed little since last month: 50 percent favor it now, while 31 percent oppose it and 19 percent are unsure. At the end of June it was 52-27 percent in favor (29-30 June 2010).

By a significant margin, Republicans favor Arizona's law (72-15 percent). Democrats are twice as likely to oppose it (by 50-25 percent), although one in four is undecided. Independents are more likely to favor (55 percent) than oppose the law (28 percent).

Regionally, those living in the West (57 percent) are the most likely to favor the Arizona law. Half of those living in the Midwest (50 percent) favor it, as do just under half of Southerners (48 percent) and Northeasterners (46 percent).

Click here to see the poll.

Arizona officials say they passed the law because the federal government was failing to enforce existing law against illegal entry into the United States. Most voters agree: 72 percent say the government is not enforcing existing laws, including majorities of Republicans (86 percent), independents (72 percent) and Democrats (59 percent).

The Arizona law took effect Thursday. It would make illegal immigration a state crime and allow local law enforcement to question the legal status of anyone stopped on suspicion of a crime, and detain anyone who cannot prove his or her immigration status. The Justice Department filed suit challenging it, and on Wednesday a federal judge ruled that many of the law's key provisions were unconstitutional.

The national telephone poll was conducted for Fox News by Opinion Dynamics Corp. among 900 registered voters from July 27 to July 28. The judge issued her ruling before half of the interviews were conducted. Even so, the results from the first and second nights of polling on the law show no statistical difference. For the total sample, the poll has a margin of sampling error of plus or minus 3 percentage points.

A mid-July Fox News poll found that voters opposed the U.S. Justice Department's challenge of Arizona's immigration law by a wide 59-29 percent margin, and a 55 percent majority would favor their own state passing an immigration law.

Voters are sharply divided over how to handle illegal immigrants currently in the United States. Nearly half — 49 percent — favor setting up a system for illegal immigrants to become legal residents. That's essentially unchanged from 50 percent in May 2009. A slightly smaller number — 45 percent — favor deporting as many as possible. Forty-three percent favored that option last year.

A 58 percent majority of Democrats favor creating a system for illegal immigrants to become legal, while a 54 percent majority of Republicans favor deporting as many as possible.

Less than a third of voters (30 percent) say immigration will be "extremely important" to their vote for Congress this year, ranking it well below the economy (57 percent "extremely important"), health care (51 percent), the federal deficit (44 percent) and taxes (40 percent).

Some 35 percent of voters approve of the job President Obama is doing on immigration, while 54 percent disapprove. This is one of his lowest approval areas. The only area where Obama does worse is the federal deficit — 31 percent approve of how he's handling that issue.

Click here for the raw data.