(Adds background, reaction from analyst and conservatives)
By Richard Cowan
WASHINGTON, Jan 12 (Reuters) - South Carolina Governor Nikki Haley, in the Republican response to President Barack Obama's State of the Union address on Tuesday, seized the spotlight to set herself apart from her party's field of presidential candidates, calling for tolerance on immigration and civility in politics.
In what some saw as a rebuke of Republican front-runner Donald Trump, Haley said: "During anxious times, it can be tempting to follow the siren call of the angriest voices.
"We must resist that temptation. No one who is willing to work hard, abide by our laws, and love our traditions should ever feel unwelcome in this country."
The 43-year-old daughter of Indian immigrants is being mentioned as a possible Republican vice presidential candidate.
"Immigrants have been coming to our shores for generations to live the dream that is America," she said.
Haley spoke from Columbia, South Carolina, where she gained national attention last year by leading an effort to remove the Confederate battle flag from the state Capitol grounds after the killing of nine black churchgoers in Charleston.
Her remarks on Tuesday sparked a backlash from some conservatives. Ann Coulter, a conservative columnist and frequent television talk show guest, tweeted, "Trump should deport Nikki Haley."
Immigration has been a dominant theme in the Republican presidential campaign for the Nov. 8 election to replace Obama. Trump has aroused controversy with his fiery comments, saying that if elected, he would build a wall on the border with Mexico to keep out illegal immigrants and force Mexico to pay for it.
The billionaire businessman has said he will deport the country's 11 million illegal immigrants. He began his campaign in June by saying Mexico was sending criminals and rapists to the United States.
Haley, whose televised remarks came minutes after Obama delivered his final State of the Union speech to Congress, issued many standard Republican attacks against the president, criticizing his fiscal policy and landmark healthcare law, known as Obamacare.
She promised that if a Republican wins the November election, working families' taxes will be cut and "runaway" spending will be constrained.
The State of the Union response by the incumbent president's political opponents is a tradition dating back to 1966.
It is a tough assignment, lacking the theater of the State of the Union itself, which takes place in the historic House of Representatives chamber, filled with lawmakers, diplomats, Supreme Court justices and sometimes celebrity guests.
A hodge-podge of politicians have been assigned to the duty, ranging from then-Democratic Governor Bill Clinton in 1985, who went on to serve two terms as president, to ex-Republican Governor Bob McDonnell of Virginia in 2010, who is now appealing a 2014 conviction on corruption charges.
Unlike Coulter, others lauded Haley. Democratic strategist Donna Brazile tweeted praise for the governor's recounting of the response to the Charleston church shooting.
Michael Needham, head of the conservative Heritage Action group, said Haley offered "a winsome message" and "painted an authentically optimistic vision for America's future."
On foreign policy, Haley said the United States faced "the most dangerous terrorist threat our nation has seen since September 11th, and this president appears either unwilling or unable to deal with it."
Lethal attacks by militants last year, including in Paris and San Bernardino, California, have made national security a major campaign issue.
Trump reacted to the California shootings by saying Muslims should be temporarily banned from entering the United States. Another Republican contender, Texas Senator Ted Cruz, has said Christians, but not Muslims, should qualify for refugee status.
Haley made no gaffes in her speech of less than 10 minutes, which was delivered in a relaxed, sometimes monotone voice.
David Woodard, a political science professor at Clemson University in South Carolina, noted Haley touched on religious and social issues that will "help some with the GOP base."
But he said the speech was too light on foreign policy concerns, including the Middle East, that voters worry about, and lacked "edge."
In some of her most eloquent remarks, Haley recalled the Charleston shootings. "Our state was struck with shock, pain and fear. But our people would not allow hate to win. We didn't have violence, we had vigils. We didn't have riots, we had hugs."
In a criticism of acrimony in U.S. politics, Haley advised: "Some people think that you have to be the loudest voice in the room to make a difference. That is just not true ... when the sound is quieter, you can actually hear what someone else is saying. And that can make a world of difference." (Additional reporting by Ginger Gibson; Editing by Kevin Drawbaugh and Peter Cooney)
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