PHOENIX (Reuters) - U.S. Hispanics and Democratic lawmakers furious over Arizona’s harsh crackdown on illegal immigrants expect huge weekend rallies across the United States, piling pressure on President Barack Obama to overhaul immigration laws in this election year.

People hold signs as they protest against Senate Bill 1070 outside the Arizona State Capitol in Phoenix, Arizona April 25, 2010. REUTERS/Joshua Lott

Protest organizers said on Wednesday outrage over the Arizona law -- which seeks to drive illegal immigrants out of the state bordering Mexico -- has galvanized Latinos and would translate into a higher turnout for May Day rallies in more than 70 U.S. cities.

“The marches and demonstrations are going to be far more massive than they otherwise would have been,” said Juan Jose Gutierrez, a Los Angeles rally organizer who runs an immigration assistance company.

The backlash began on Friday after Arizona Governor Jan Brewer signed into law a measure that requires state and local police to determine a person’s immigration status if there is “reasonable suspicion” they are undocumented. Critics say it is unconstitutional and opens the door to racial profiling.

Republican backers of the law say it is needed to curb crime in the desert state, which is a key corridor for drug and migrant smugglers from Mexico.

A Rasmussen Reports poll on Wednesday found that almost two-thirds -- 64 percent -- of voters in the state favored the measure.

The crowds on the streets, from Los Angeles to New York, could be the biggest since 2006, when hundreds of thousands of marchers urged former President George W. Bush to overhaul of federal immigration laws. He tried, but failed in Congress.

“With what’s going on in Arizona we see renewed energy for folks to fight for immigration reform,” said Marissa Graciosa, of the Fair Immigration Reform Movement, an organizer of rallies and vigils on Friday and Saturday.

In Washington, a diverse group of more than two dozen lawmakers -- Hispanics, blacks, Asians, whites -- held a news conference outside the U.S. Capitol on Wednesday to denounce the Arizona law as a violation of civil rights.

“What Arizona has done is that it has galvanized, united, fortified, focused our immigration movement,” Democratic Representative Luis Gutierrez declared at the news conference.

MEXICAN TAXI BOYCOTT

The Arizona law has catapulted the immigration issue back to the front and center of U.S. politics in this congressional election year, and ratcheted up pressure on Obama to keep a pledge to Hispanics to pass comprehensive immigration reform.

“It is going to allow us to ultimately say -- when all is said and done -- that this was the clear pivotal moment,” said Gutierrez, who is head of the congressional Hispanic caucus’ immigration task force.

U.S. Senate Majority leader Harry Reid, who faces a tough re-election battle in Nevada where Latinos helped clinch victory for Obama in 2008, said on Wednesday he would work to pass energy legislation before tackling immigration reform, although both are seen as election-year long shots.

Passing an overhaul offering a path to citizenship for many of the 10.8 million illegal immigrants in the United States would consolidate support for Democrats among Hispanics, the country’s largest minority, but would run the risk of energizing Republican opposition to Democratic lawmakers in swing states and districts.

Arizona’s bold move reverberated well beyond its borders, sparking calls for economic boycotts and celebrity interventions.

Colombian-born pop star Shakira said she will travel to Phoenix on Thursday to help campaign against the new law, and would meet with Mayor Phil Gordon, police and Latino families. She sought a meeting with Governor Brewer but was turned down, her publicist said.

Adding to calls to shun the state, Saint Paul, Minnesota, Mayor Chris Coleman on Wednesday banned publicly funded travel to Arizona. The state law set a “dangerous example to the rest of the country,” he said, by creating a culture that made racial profiling acceptable.

The National Conference of State Legislatures said similar state immigration enforcement laws may be proposed in Georgia and Texas in coming months, following a summer recess.

In Mexico, where the government has warned its citizens living in or traveling to Arizona that they could be harassed, taxi drivers organized their own peculiar boycott.

“We don’t give service to gringos from Arizona,” was the phrase some Mexico City taxi drivers painted in white on their rear windows.