Anxious Republican officials are coming to terms with the idea that their second least favourite presidential candidate - polarising Texas conservative Ted Cruz - may be the party's best last chance to stop Donald Trump.
Reluctant Senate colleagues and former presidential rivals have long feared Cruz's purist ideology but fear the prospect of a Trump nomination more.
The first-term Texas senator has gained the support of one former primary opponent, Carly Fiorina, and is seeking the backing of another, Jeb Bush, on Thursday.
South Carolina Senator Lindsey Graham says Cruz is "the most logical person to take on Trump". Earlier in the year Graham likened the choice between Cruz and Trump to "being shot or poisoned".
Trump, meanwhile, is calling on mainstream Republicans to unify behind his candidacy.
In his own unorthodox way, Trump is evolving into a general election candidate.
The over-the-top billionaire is talking about flexibility in his hardline immigration policies. He's pledging to moderate his bullying tone, acknowledging that women in particular may be turned off by his brash brand of politics.
And he's working at assuming the mantle of GOP standard-bearer, calling for party unity and promising to help fellow Republicans.
Trump is still doing things his way.
His pledge to help other candidates came just before a lengthy promotion of his brand, all while flanked by tables of Trump wine - as well as bottled water and steaks, which he no longer sells.
His calls for party unity are still bracketed by jabs at rivals "Little Marco" Rubio and "Lying Ted" Cruz.
