Heraldo de Madrid - A Trump challenge: uniting bitter Republicans

Trump is basking in the glory of an all-but-certain victory in the chaotic GOP nomination race, after rivals Ted Cruz and John Kasich raised their white flags of surrender.

But Trump's rise presents a moment of truth for Republicans: can they rally around one of the most contentious presidential nominees in modern history?

Astounding displays of antagonism are coming from conservatives who under more normal circumstances would likely be backing the Republican standardbearer.

Startling images landed on Twitter Tuesday and Wednesday in the hours after the braggadocious billionaire's sweeping Indiana primary victory, including a shot of conservative writer Lachlan Markay and video of one Bryan Akner, both setting their voter registration cards alight.

One of the chief challenges on Trump's hands as he shifts from the nominations battle to a likely general election brawl against Democrat Hillary Clinton is how to win over Republicans infuriated by his candidacy.

Some conservative critics like former candidate and Louisiana ex-governor Bobby Jindal, who once branded Trump "dangerous" and ignorant, are biting the bullet and shuffling into line behind Trump.

Mainstream Senator Susan Collins said she would support Trump, but he will "have to mend a lot of fences" and halt what she called gratuitous insults that have marked his campaign.

The country's previous two Republican presidents, George W. Bush and his father George H.W. Bush, who undoubtedly bristled at Trump's bullying attacks on candidate Jeb Bush, have signaled through their offices that they will stay on the sidelines during this cycle.

George W. Bush "does not plan to participate in or comment on the presidential campaign," his personal aide Freddy Ford told the Texas Tribune.

Other Republicans are sounding like they intend to fight Trump every step of the way -- by voting for Clinton, if necessary.

- 'I'm with her' -

"The GOP is going to nominate for president a guy who reads the National Enquirer and thinks it's on the level," tweeted Mark Salter, a former senior advisor to 2008 Republican nominee John McCain, after Trump peddled the tabloid's conspiracy theory that linked Cruz's father to president John F. Kennedy's assassin.

"I'm with her," Salter added, repeating a Clinton campaign slogan.

Washington Examiner's managing editor, Philip Klein, tweeted that he had "officially de-registered as a Republican."

Erick Erickson, a respected conservative blogger, on Wednesday blasted Trump for supporting "white nationalists and racial grievance mongers," mistreating employees and bragging about his philandering past.

But he also took issue with the party's failure to "draw a line" against Trump's bigotry and insults.

"Why can't the GOP say this is unacceptable?" Erickson wrote on The Resurgent website, insisting he will "decline to help the voters in this country commit national suicide."

With Trump the presumptive nominee, the Republican Party was trapped in a balancing act of promoting their man while soothing the frustrations of the NeverTrump movement.

"There are some raw feelings out there," Republican National Committee spokesman Sean Spicer acknowledged on MSNBC.

Conservative lawmakers including Senator and former presidential candidate Lindsey Graham, Senator Ben Sasse and congressman Justin Amash, as well as 2012 GOP nominee Mitt Romney, are on a list compiled by The Hill of nearly 100 prominent Republicans who have pledged not to vote for The Donald.

Sasse said Wednesday he remained open to a third candidate, beyond Trump or Clinton, who would promote conservative values.

"I think some Republicans in the establishment will hold their nose and give tepid support to their nominee Donald Trump," senior fellow John Hudak of Washington think tank the Brookings Institution told AFP.

"But I think there's going to be a significant number of establishment Republicans who frankly will continue to run against Donald Trump," including some who "come out and endorse Clinton."

The NeverTrump movement, meanwhile, signalled it would continue to seek opportunities to oppose his nomination, and to help conservatives, particularly by "protecting Republican incumbents and down-ballot candidates, by distinguishing their values and principles from that of Trump."

Should Trump pivot from some of his divisive statements to a more presidential tone, he might draw skeptical Republicans into the voting booth to support him.

Others appear to be gone for good.

"I'll probably go with (Libertarian candidate) Gary Johnson," conservative strategist Brad Marston said.

"I don't see any room for me in today's GOP."

E.Pineda--HdM