Nikki Haley, the Republican who took on Trump

On Tuesday night South Carolina Governor Nikki Haley delivered the official Republican response to President Barack Obama's State of the Union address - but there was more to it than that.

Her 15-minute speech also served as an unofficial rebuke of Donald Trump and the in-your-face style of campaigning that has rocketed him to the top of a crowded Republican presidential field.

And while her speech won positive reviews from many in the mainstream media and high marks from at least one focus group watching the night's events, it also exposed the deep fissures within her Republican Party.

After a taking a few minutes to express disappointment with Mr Obama's seven years in office, Ms Haley got down to what has become the defining battle for the future of a Republican Party that, while achieving electoral success in Congress and state capitals over the past few years, has been roiled by a growing frustration with its politics and politicians.

Many Republican voters feel their party is out-of-touch with their priorities and ineffective in advancing a conservative agenda. It's a vein of resentment that Mr Trump has built an entire campaign around.

Nikki Haley says people like Donald Trump are engaging in "irresponsible talk"

"We as Republicans need to own that truth," Ms Haley said. "We need to recognise our contributions to the erosion of the public trust in America's leadership. We need to accept that we've played a role in how and why our government is broken. And then we need to fix it."

She recounted her own background as a child of Indian immigrants and the importance of welcoming "properly vetted legal immigrants, regardless of their race or religion" - a sharp contrast to Mr Trump's recent call for temporarily blocking the entry of all Muslims into the US.

The 43-year-old governor also noted the tolerance her state displayed following the mass shooting by a white supremacist in a predominantly black Charleston church last June.

"We didn't have riots, we had hugs," she said.

Then she offered her most pointed lines, which she confirmed on Wednesday were aimed directly at Mr Trump and others on the national stage who engage in "irresponsible talk".

"In many parts of society today, whether in popular culture, academia, the media or politics, there's a tendency to falsely equate noise with results," she said. "Some people think that you have to be the loudest voice in the room to make a difference. That is just not true."

On Wednesday morning Mr Trump responded to the perceived criticism, saying Ms Haley was "very weak" on illegal immigration. He added that she "has no trouble asking me for campaign contributions".

"Perhaps if I weren't running she'd be in my office asking me for money," he said. "But now that I'm running she wants to take a weak side on immigration."

Nikki Haley, rising star of US politics

• born in Bamberg, S Carolina, to Indian parents

• S Carolina's first woman governor, elected in 2011 and re-elected in 2014

• youngest current governor in the US

• heavily tipped to be Republican nominee's running mate

• her website boasts of huge job creation and infrastructure investment - without tax rises

• married to Michael Haley, who served in Helmand, Afghanistan

• two children Rena, 17, and Nalin, 14

While Ms Haley's speech was pitched as a call for tolerance and an attempt to put a welcoming face on the Republican Party, the reaction from some conservative quarters was anything but accepting.

"Trump should deport Nikki Haley," tweeted conservative firebrand Ann Coulter, a passionate supporter of the billionaire-turned-candidate.

According to Breitbart's John Nolte, Ms Haley - chosen to give the Republican response by the Republican leaders in Congress - was just the latest attempt by a party establishment that is desperate to derail Mr Trump's campaign.

"To use the State of the Union response to publicly attack her own frontrunner must be unprecedented, and certainly serves as more proof to Trump's supporters that the Republican Establishment is much more interested in DC media love than winning elections and advancing their legislative agenda," he writes.

"For the good of the country, this suicidal Republican Establishment temple must come down and be ground into dust," he concludes.

Another Breitbart writer referred to Ms Haley by her full name - Nimrata Randhawa Haley - and expressed mock surprise that she would have "no clue about America's heritage".

Amanda Carpenter, a former staffer for Senator Ted Cruz, a Republican presidential hopeful who also regularly rails against his party's leadership, was equally dismissive.

"Nikki Haley's speech would've been good except for the GOP self-loathing," she tweeted.

Ms Haley gained national prominence after the shootings last June at a predominantly black Episcopal church in Charleston, South Carolina

Thanks to her performance following the Charleston shootings, where she successfully coaxed South Carolina's legislature into removing the controversial Confederate battle flag from the state capitol grounds, Ms Haley has been advanced by some as a possible vice-presidential candidate for whoever ends up winning the party's presidential nomination.

They pitch her as a young, charismatic face of a party seeking to broaden its base of support to counter the diverse electoral coalition assembled by Mr Obama during the past two presidential elections.

If this week is any indication, however, such a move may only deepen the divides within the party.

"The Haley speech was an echo of George W Bush, Jeb, Lindsey Graham-style Republicanism," tweeted conservative radio host Laura Ingraham. "We'll see how popular these views are as primaries begin."